I have written a very rudimentary wikipedia offline reader. It can be downloaded at http://test.wikipedia.org/upload/WINOL.zip
This contains the current source (GPL), and a Windows exe. You'll also need the SQL dump (better stick to en;-)
For those few how tried the last version: Get this one! It doesn't need the conversion anymore, it reads the articles right from the SQL file.
You'll have to run the "Tools/Index" once on the SQL file, though. This will create a ~4 MB index of the article titles and the position of their data set in the SQL file. Takes about 1 min.
Don't expect too much from this version. You can browse the 'pedia, read all the text and see most of the formatting, but that's about it. No images, no offline edit, no search function. Yet.
Magnus