Lost in the Yahoo-Microsoft hullabaloo last week was Yahoo!'s entrance into the lucrative online poker industry. Through Yahoo! UK & Ireland, Yahoo! becomes the first major internet company to offer real-money poker, an incredibly profitable business.

Yahoo partnered with St. Miniver Ltd., a gaming network operator from Gibraltar, to join the International Poker Network (IPN) operated by Boss Media AB, a Swedish software provider. IPN consists of 21 different poker sites with a large presence in continental Europe. The site is live here.

Ryan McLean from Casino City Times sums up the potential impact that Yahoo will have on the emerging online poker industry and publicly traded companies like 888 Holdings (888.L), and Party Gaming (PRTY.L) and large private competitors like Poker Stars. Yahoo spokesperson C.J. Stanley, meanwhile, threw down the gauntlet: "The established gaming sites such as Party Gaming and 888 will be concerned and if they are not, they should be."

A quick check of the online poker traffic reporting site, PokerSiteScout, indicates that the IPN network is currently the 12th largest poker site with 1,287 cash players per day, trailing larger sites like PokerStars and PartyPoker that average 7,000-9,000 cash players per day. Expect Yahoo! to use its strong brand and popular casual gaming business to quickly propel the IPN to the top of the rankings.