I know that Yahoo will love it, provided the pages are optimized for “world series of poker”.
Seems that Yahoo has a bias towards domain names that carry the key phrases.
Google has about 1.5 million SERPS for that phrase, which isn’t that much for a gambling phrase – with good SEO, including backlinks, it should do very well.
I dont’ know about the trade mark thing, though. You can do a search for it at some trademark sites online, but I haven’t found a free search service yet.