The Common Sense Gamer published a reality checking rant on the coming wave of mobile MMOs. The author of the editorial pointed out that limitations in the technology and a lack of platform standards in the industry will only lead to mediocre if projects. He also suggested that users who aren't near wi-fi hotspots won't be able to get much done.
He probably hasn't used a 3G phone yet; 3G networks are plenty fast. But for the most part, the rant was insightful -- especially on the issue of standards. All these cell phones use totally different platforms for running games, and they vary widely in performance and power. Is it feasible to develop for a dozen different platforms at once? Most game developers have enough trouble as it is with three!
So maybe the best we can hope for is a Snake MMO. Actually, that could be kind of cool.