No server-side code allowed, but you can work all the jquery magic you want and they have a facility for static pages with arbitrary URLs. I'd probably not recommend selling it to a business, because, for example, here's how I'd do an image gallery:

1) upload the pics to flickr 2) use jquery to grab the pics 3) make a static page to display them

Also, because it's clear that their service is designed for single-person blogs, their group blogs have some annoyances that range from minor to severe.