As AOL CEO Tim Armstrong works to integrate his $315 million purchase of the Huffington Post into the Internet portal, one of its top advertising leaders is departing for a big job at Yahoo.

Mark Ellis will become head of the Silicon Valley Internet giant’s North American field sales, afterhttp://kara.allthingsd.com/wp-admin/my-sites.php serving in a wide variety of jobs at AOL and being a key lieutenant to global ad sales head Jeff Levick.

Previous to AOL, Ellis worked at sports marketing company IMG, at Quokka Sports, a sports Web site and at Time Inc. as publisher of Time Inc. New Media.

While there, he worked with Yahoo’s current U.S. ad sales head Wayne Powers.

While AOL portrayed the move as a well-planned reorganization in an internal memo, the departure of Ellis was a new wrinkle, as Armstrong has been contemplating how to best rejigger its key ad business after the bold acquisition of the news and opinion site run by its famous editor-in-chief Arianna Huffington.

Several sources said Armstrong found out a week ago about Yahoo’s interest in hiring Ellis, whom Yahoo had been pursing Ellis for far longer. Interestingly, he has been involved in the planning for the changes as the deal to buy the Huffington Post wraps up.

Sources said that deal is expected to close as soon as a week.

Previous to the Huffington Post situation, sources at AOL said the New York-based company has been contemplating a variety of changes, including Ellis’ role, in the ad department as its sales have continued to suffer.

Whatever the circumstances, an experienced ad sales exec like Ellis moving to a major AOL competitor is certainly a change.

Here is Levick’s staff memo on the changes in AOL’s ad unit, with the Ellis move buried low and with no mention of Yahoo (natch!):

Team–

One year ago this week, we decided to innovate the future of brand advertising for the digital world. Last night, our work was recognized by the industry in a meaningful and significant way. The race is on for the next phase of advertising on the Internet and we are in that race. We have more to do, but we’re going to do it and do it quickly.

Today, we also wanted to announce a set of changes that will allow us to expand and accelerate our ability to serve our customers on a deeper level. We now have a great suite of products to match our talented team. We also have an expanding base of consumers on some of the best brands on the Internet and that represents a very attractive proposition for our customers. The addition of The Huffington Post adds an incredibly talented team of sales people and journalists to our team and we have the ability to scale all aspects of our business.

I’m very happy to announce that over the next 90 days, we will be integrating The Huffington Post sellers into our regional teams and expanding the roles of three of our star field generals–Tim Richards, Wendy McGregor, and Tim Castelli. Wendy, Tim, and Tim will lead the sales for AOL and Huffington Post Media Group and report directly to me, moving them into a more central role in AOL’s revenue strategies and management.

Jim Norton will continue to lead the Advance Sales team but will also be taking on a new role as the VP of Product Sales, reporting into me. In this role, he will help realize the potential with Mail, AIM, Local, AOL.com and other core product solutions for National and Advance advertisers, serving as a critical ‘linchpin’ that connects our advertiser opportunities with AOL solutions. Christa Zambardino will continue to lead sales efforts for AOL.com and will report to Jim.

Don Kennedy will also report directly to me, taking our focus on the network to new levels and will continue to build out our Network Sales organization, working in close partnership with Dave Jacobs and Rob Luenberger.

Finally, Mark Ellis will be leaving the organization. I can’t thank Mark enough for all he has done for AOL and for the teams during his time here. He has been a great partner to me and I wish him all the best in his future endeavors.

We will continue to keep you updated on the status of the Huffington Post deal as well as any other organizational announcements. Please feel free to reach out to me with any questions.

Best,

Jeff

More moving of the chairs at AOL’s Platform-A.

The Time Warner (TWX) online unit will announce today that Mark Ellis has been promoted to EVP of sales at the advertising division.

He will lead Platform-A’s digital ad sales, sources said, including premium efforts at AOL’s MediaGlow content unit and for its third-party ad network.

It is all part of extensive management reorganization being done by Platform-A President Greg Coleman, former sales head at Yahoo (YHOO).

New CEO and Chairman Tim Armstrong started yesterday and told staff in a memo that even more change was coming, as part of a 100-day effort to evaluate how to revive the online company.

Ellis has been at AOL for a while, most recently as SVP of vertical and product sales. Previously, he worked at sports marketing company IMG, at Quokka Sports, a sports Web site and at Time Inc. as publisher of Time Inc. New Media.