I've proposed a short talk on Pack200 in Eclipse and how it works. As you probably know, Pack200 is the compression algorithm for Jar files that can reduce them by around 50%, and Eclipse has had the ability to use Pack200 Jars for downloading updates, so the first minute or two are how you can create pack200 sites for faster downloads.
The last couple of minutes will be on how Pack200 works. I'm working on an open-source Apache License version for Harmony, so I've been digging into the details of how it manages to achieve its level of compression. I won't be going into a huge technical diatribe (it is, after all, a 5 minute talk) but I'll be putting together a few graphic illustrations of what it does to achieve some of the levels of compression that it gives.
If you're interested in finding out more, vote for or add your comments to bug 3908 in EclipseZilla