The answer is "pretty much as you might think." But we'll get to that. First:
The list of infected iPhone apps can be summed up as "nothing I use, so big deal." But it could be something you use, so here's the list. The apps were nastified by a cracked version of the programdevelopers use to compile the code, and according to Daring Fireball, Chinese developers used it because downloading the original from Apple took too long.
Here are some of the infected apps. Spot the fake one, if you can:
China Unicom Mobile Office
High German map
Jane book
Eyes Wide
Medicine to force