Three of the most popular iPhone apps for comics, Comixology, iVerse, and Panelfly, have begun offering a limited selection of Marvel Comics for the iPhone and iPod Touch.  Priced for between $.99 and $1.99, the three companies are offering some titles which are the same from all three companies, and others which are not. 

Titles involved in the program (not all available from all three companies) include Astonishing X-Men, Invincible Iron Man, X-23, Age of Apocalypse, Amazing Spider-Man, Captain America, and Marvel Zombies.  The total number of issues appears to be under 100 from each company.