There's very few companies out there that can take a standard iPhone built application and have it replaced with something in the App Store. tap tap tap has built a product that has replaced the default Camera on my phone and my wife's.
All of these camera Apps - Hipstamatic, Instagram, Camera+ - massive popularity. I think that the iPhone is now clearly attacking the "photography" vertical as well as the "games" vertical. I expect Jobs to spend a significant part of his next iPhone roll out describing in more detail the attention they are paying to photography on the iPhone based on recent App Store results. Also looking for a big upgrade in the (already quite useable) camera.
Must be miserable news for the point n' shoot vendors.
I bought this assuming that it had the volume control wired to take the photo, and was slightly disappointed that it didn't. I know the back story, but assumed that as that was surely the main point of the app, that this version would have it as well!
Good for them that Apple forgave them for openly flaunting the App Store rules.
http://www.iphoneography.com/journal/2010/8/12/camera-banned...
Their small team has an incredible designer, Wolfgang, who wields Adobe CS like a wand to turn around iterations of designs in near-real time.
http://taptaptap.com/blog/the-design-session/