A certain fortune 500 finance company did their entire website this way using java 6 EE and serving up the data layer with XML -> Hibernate -> DB2 mainframe queries about 10 years ago. Probably still vestiges of that now.
(Jokes aside, I tried this years ago hoping for it to be a magic bullet. Gzipping meant that the bandwidth savings weren’t anywhere near what I hoped and XSLT is a PITA to deal with)
- No JS fallback by default
- Naturally friendly to XML database backends
- Huge cache hit improvements
- Effectively, you get the functionality of the now abandoned "seamless" iframe attribute