Heat Man has just passed along word that according to Famitsu, the version of Mega Man X released to the App Store is poised to receive some new updates. No word on whether this will come to the U.S. version, though we'd say it's likely. Edit: The update is available in the US. In any case, the additions are relatively minor, with one allowing the game to fit the screen of the iPad and iPad 2, whereas it was originally scaled for the iPhone with an option to double the size. The other part of the update is a new mode called Time Attack.
In Time Attack mode (called Time Race in the Japanese game), where your life bar is replaced with a swiftly depleting time gauge. The game is over when you run out of time, but enemies drop time replenishing items. Enemy placement is somewhat altered as well. You also get a "T Tank" in the boss gate which gives you a full time gauge with which to fight the boss.
If you're unfamiliar with the game, you can find a handy review here.