Although an unofficial computer game version of BANG! has been released in the past (which is great despite a few bugs, and only containing the original game with no expansions), there is an official version being created by Palzoun that looks really cool. They have posted some trailers on their site. Here is their gameplay video:
Check out for more information at Palzoun's blog or at the official site.
From my initial look at the gameplay video, it looks graphically very nice, and seems to explain the game and its rules pretty well to newcomers. My concern is that the game looks abysmally slow. I don't want cards shaking in anticipation for a "draw!" or long graphical effects for Duels. Perhaps this can be customized, sort of like Hasbro's Star Wars Monopoly, so that you can cut it to the nuts and bolts if you want it to. I sure hope so because I won't be able to tolerate the long waits otherwise. KBang doesn't have this issue, and may be a much more enjoyable game than this official version if this continues. Besides this, players' cards seemed a little hard to see, even scrunched. I am curious how well you will be able to see things on an iPhone in a 7-player match. But we'll see how it turns out when it is released. Supposedly it is slated to come out this Christmas, but that looks doubtful as it is already December 12.