London-based open-source ad server startup OpenX is biting the bullet and moving to Los Angeles. In addition former Yahoo senior vice president Tim Cadogan will take the CEO job at the startup by Index Ventures, Accel Partners and others, reports Kara Swisher. OpenX has about 30 employees, including 10 developers in Poland, but not all will head to the US. This is probably a necessary strategic move for the ad company, heading to the capital of media and entertainment, but it’s a shame to see it move out of London.

Cadogan, who was with Yahoo for five years in its search unit and was later SVP for ad products. OpenX (which recently and controversially changed its name from OpenAds) serves about 30,000 Web publishers on 100,000 Web sites in more than 100 countries. OpenX has raised about $21 million in funding since 2007. Besides Index and Accel, other investors include First Round Capital, Mangrove Capital and O’Reilly AlphaTech Ventures. Former AOL head Jon Miller also recently joined its board as chairman.

Whether current CEO James Bilefield, another former Yahoo exec and British national, is going or staying in some other capacity is something which I am looking into right now. However, he doesn’t appear to be staying on as Skype’s European general manager, a role he had combined with OpenX.

Update: OpenX says James Bilefield will stay with them “through the transition and as an adviser to the company” – which doesn’t exactly sound like a long term arrangement.