For my GSoC project Incremental data dumps [1], I'm creating a new file format to replace Wikimedia's XML data dumps.
A sketch of how I imagine the file format to look like is at http://www.mediawiki.org/wiki/User:Svick/Incremental_dumps/File_format.

What do you think? Does it make sense? Would it work for your use case?
Any comments or suggestions are welcome.

Petr Onderka
[[User:Svick]]