Mobileread member
amirshim has created a method for browsing Wikipedia on the iLiad without being connected to the internet. His solution features a mini dump of Wikipedia, however, a full version is possible as well, with a bit more work.
You can find instructions for setting it up yourself on his project page.
I've created a package out of it that you can simply download, unzip, and copy to a memory card for your iLiad.
You can find that installer here. (beware 54MB File)
Join the ongoing discussion in this thread.