One of Microsoft’s top execs, Debra Chrapaty (pictured here), who heads its infrastructure business, is leaving the software giant to take a top job at Cisco (CSCO), sources said.

Chrapaty–whose title is corporate VP of Global Foundation Services–is also one of increasingly few top women tech execs at Microsoft (MSFT), where she has worked for seven years.

The job put her in charge of, as a Microsoft site notes, “strategy and delivery of the foundational platform for Microsoft Live, Cloud and Online Services worldwide including physical infrastructure, security, operational management, global delivery and environmental considerations. Her organization supports over 200 online services and web portals from Microsoft for consumers and businesses.”

In other words: A lot of plumbing.

She was featured onstage with other key execs at Microsoft’s Financial Analysts Meeting earlier this summer.

Sources said Chrapaty will now shift to products at Cisco, running the collaboration software group.

That unit’s former exec, Doug Dennerline, recently moved to Salesforce.com (CRM) to take a job as its EVP of sales for the Americas.

At Cisco, as had Dennerline, Chrapaty is likely to play a large role in forming the networking giant’s cloud computing and software-as-a-service strategies.

Chrapaty has worked at a lot of tech companies, including Organic, AllBusiness and Etrade Technologies. She was also CTO of the National Basketball Association.

Well-known Silicon Valley entrepreneur Reid Hoffman (pictured here) will become CEO of LinkedIn again, taking on the job he had for nearly four years after founding the business networking company in 2003.

Hoffman replaces current CEO Dan Nye, who has resigned and will leave the company in mid-January. He came to LinkedIn almost two years ago and was positioned then as the person who was going to eventually be taking LinkedIn public.

More interesting in the shift is the appointment of former Yahoo exec Jeff Weiner as interim president, overseeing day-to-day operations at LinkedIn.

Weiner has been an executive-in-residence at both Accel Partners and Greylock Partners (a LinkedIn investor) since he left Yahoo earlier this year.

He will remain at those venture firms during the transition, even though he will be working at LinkedIn too. At Yahoo (YHOO), Weiner was EVP of the Network Division, which included all of its consumer-facing units.

In an interview earlier today, Hoffman portrayed the changes as friendly, praising Nye’s efforts as top exec, noting the company’s growth from eight million members to 33 million, reaching profitability, and its $53 million in funding in June at a $1 billion valuation.

But, Hoffman said, “We came to the decision that I needed to be working full time, driving the vision.”

Nye (pictured here) noted the recent hiring of Google (GOOG) exec Dipchand “Deep” Nishar as VP of products, which he spearheaded, was an important moment. Hoffman had been in charge of products.

“I wanted to grow this company into a world-class operation,” he said. “Now, Reid needs no friction, so he can move quickly and do what’s necessary for the next phase.”

Weiner (pictured here) said he was looking forward to getting back into operations, after playing an advisory role recently. “I have been really impressed with the company the leadership team has built,” he said. “I see a lot more potential going forward.”

Although it has raised $100 million in total, LinkedIn has not been immune to the recent economic weakness across Silicon Valley. It recently did some layoffs too, and has been focusing much more on increasing the number of revenue streams it has.

Below is a video interview I did with Weiner in June of 2007, when he was still at Yahoo.

And, below that is another I did with Nye, nine months after he first got to LinkedIn, in which he talks about his plans for the company. (Yes, that is a Hawaiian shirt, and Nye does give Yahoo advice in it.)

Weiner:

Nye:

In a much-expected financing, LinkedIn has joined the big funding club (Slide, Spot Runner) of late, by raising $53 million at a startling $1 billion valuation.

Why go public when you can just pretend?

Actually, unlike a lot of Web 2.0 start-ups, the professional networking site, which had 23 million active monthly members in June, has been profitable since 2006.

According to execs, it has revenues of about $100 million a year, from premium subscriptions and job listings, as well was advertising and corporate sales.

The new slug of cash comes from new investor Bain Capital Ventures, along with existing investors Sequoia Capital, Greylock Partners, and Bessemer Ventures.

LinkedIn had previously raised $27 million for a total of $80 million. Yipes!

“This additional funding will give us even more flexibility to execute on our vision for millions of professionals to increase their effectiveness by using LinkedIn to build relationships and exchange knowledge, opportunities and advice,” wrote LinkedIn CEO Dan Nye (pictured here) in a blog post tonight.

In an interview with LinkedIn’s founding CEO and Chairman Reid Hoffman (pictured here) today, he told BoomTown that the money raised would be used for corporate development and acquisitions.

“We’ll be doing small technology acquisitions to improve our service,” said Hoffman. He also noted that it was unlikely the company would be doing an IPO in the immediate future, which has been bandied about.

“We have no immediate plans” for a public offering, said Hoffman. “We still have a lot of ground to cover to grow.”

Comparing the the business-oriented LinkedIn professional network with hot social networks like Facebook, Hoffman noted: “They have page views and time on the site and are looking for a scalable economic model and we have an economic model and will focus on growing usage.”

LinkedIn certainly has been growing its coffers. It raised $5.2 million in its first round, $10 million in its second and $12.8 million in its third.

Here is a video of LinkedIn’s investors trying mightily to play down the $1 billion valuation, while also pumping it up.

You gotta love the cheerleading of Greylock’s David Sze, Bessemer’s David Cowan and Mark Kvamme of Sequoia, along with new investor Jeffrey Glass of Bain (who will join LinkedIn’s board as an observer):