The press release is almost done at:
http://commons.wikimedia.org/wiki/Commons:Press_releases/100K
If someone wants to write a background section on what wikis are etc., that might be a useful addition. Beyond that, please make minor fixes, and help to translate it into as many languages as possible. We can start sending this out on Monday. It doesn't need to be done in all languages simultaneously; if some need a few more days, that's fine.
As noted in the release, the 100,000th file, by my count, is: http://commons.wikimedia.org/wiki/Image:Dataflowfiringnodes.png
All best,
Erik
wikimedia-l@lists.wikimedia.org