If you've noticed more people on the bus or at the airport playing "Tetris" or "Sudoku" on their mobile phones, you're not alone. According to research firm Telephia, videogames on cell phones reached a record $151 million in the U.S. in the last quarter of 2006. That's up 61 percent from the same three-month timeframe in 2005. Nearly 17.4 million mobile consumers downloaded a game in October, November and December of last year, which is up from the 12 million consumers a year earlier.

And unlike console games, which are still the domain of males 18 to 34 (despite the success of the Wii), 65 percent of all games purchased on a mobile device are by women. Forty percent of all games purchased are by consumers ages 25 to 36, which also skews a bit older than console gamers. With this mass market demographic to work with, game publishers are having great success with casual games, arcade games and word/puzzle games.

The one thing that is consistent with the console world is that EA Mobile has the largest piece of the pie with 28 percent of total revenue. Ever since EA purchased Jamdat Mobile, it's been a major player in this burgeoning market. Other big players in the mobile gaming space in the U.S. include Glu Mobile and Gameloft, which owned 11 percent of Q4 sales. The rest of the pie was divided amongst Namco, I-Play, Digital Chocolate, Hands-On Mobile, Superscape, Capcom and Oasys Mobile. Overall, there are 90 mobile game publishers active in this lucrative space.

Look for mobile games to continue to lure more consumers, including key gamers, as 3D graphics are already providing gameplay experiences close to a Nintendo DS. With Nokia's next generation N-Gage platform launching across multiple phones later this year, there will be a lot of advanced games hitting the global market. It's easy to keep the mass market happy with mainstream games, now companies are looking to lure more of the dedicated gamers away from Nintendo DS and PSP.