Blogging with the iPad is possible, but requires a slightly lateral approach.
The Safari browser lacks the capacity to upload images, so if that's what you want to do, it becomes a two-stage process.
First, you need to compose the post, including any images, and save it as a document. In this case I've used iWorks.
Then you send it to your regular computer, (using email or the MobileMe application) and post it from there. You can make a text-only post if you want to complete the whole exercise using only the iPad.
Apparently there are browsers being developed for the tablet which overcome the problem, but for now I'm happy to keep using Safari until I build up my skill base.
This is the finished product. The pic is for illustrative purposes only.