Now that I am using wordpress 2.7, I thought it would be good to test the iPhone app for wordpress. This is written on the app itself. I would say that although useful it seems to be more favorable to blog from a computer. The iPhone is suited to short spurts of typing, more on the realms of SMS or twitter.
The capability of quickly adding photos and the tag/category functionality seems full featured, as shown by a photo of my dinner I made from Cook with Jamie.