Readers of Marvel Comics have can purchase and read comics on their iPhone through no fewer that four apps according to this press release...

Get Marvel Digital Comics! YOUR Choice How!

These apps come from iVerse, Panelfly, ComiXology, and ScrollMotin (Iceberg reader?). Comic books can be purchased using the in-app purchase mechanism. I downloaded and installed PanelFly's app to test out this process since Marvel comic books are 99 cents each through this app compared to the $1.99 cost in other apps (noted by MacWorld's article below).

Marvel Comics come to iPhone

Panelfly Comics 1.1 (iTunes App Store)

Note that only a few comic titles and issues are available via these iPhone apps. And, the various iPhone apps do not offer the same comic titles for in-app purhcase as noted by Comics Book Resources...

Marvel Comics now available via comiXology, iVerse, Panelfly and ScrollMotion apps [Updated]

For exampl,e Spider-Man and Iron Man titles are available through PanelFly but not comiXology. On the other hand comiXology appears to be the sole iPhone app source for Captain America and Marvel Zombies.

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The app purchase process is simple: Tap on the price ($0.99 here). The price circle changes to "Buy Issue".

Tapping on "Buy Issue" results in the comfirmation pop-up window seen above. Tapping on "Buy" took me to a login prompt to authenticate my iTunes account information.

The downloading process took what seemed like a few minutes (perhaps 2) over a WiFi connection.

The comic book reading experience was so-so. PanelFly's app didn't respond quickly to my finger gestures on a 1st generation iPod touch. It seemed to take at least 3 or 4 swipes before each page turn. This experience might be better (faster) on the faster iPhone 3GS or 3rd generation iPod touch. The wide variety of panel sizes did not fit well in the iPod touch's small display. I should note that I was quite satisfied with the way the ComicZeal app handled page turns (fast) and panel displays. I may have to buy another issues using comiXology to see if that app deals with page turns and panel displays better.