Blogger has just released an iphone app. I downloaded it to my ipad to try out in case I see something of interest when I'm out and about. So far so good but not quite as easy as using the traditional keyboard.
It does allow for photos to be uplaoded straight from the ipad which may be a useful feature. I've added a photo of the Giant's Causeway.
I will see if I find it useful and let you know.