It looks interesting... I'm always on the look out for something to replace Simplenote on my iPod, not because it's not good - it is, but to because the free version has ads and it not possible to buy it without. It's necessary to subscribe which I don't really want to get into. Markdown formatting and Dropbox make it worth a try.

Just found this app last week while my MBP was in for repairs. Had to do some Markdown writing with the only thing I had, an iPod touch. WriteUp worked the best for writing in Markdown (with the aux keyboard) and the export options were great for what I needed—my normal Scrivener to TextMate post-process was unavailable, so the export as HTML was great for prepping it for my blog.

WriteUp really saved my day!