pages-articles.xml.bz2 – Current revisions only, no talk or user pages. (This is probably the one you want. The size of the 4 April 2013 dump is approximately 9.06 GB compressed, 42 GB uncompressed)
bzip can be decompressed in chunks, can't it? I wonder if there's an app to read a compressed wikipedia xml archive on an ios or android tablet. Even better would be if it fetches missing resources (like embedded images) from the real wikipedia if there's internet access.
Almost 9 GB, though it's significantly smaller if you download the version without images (which my Wikipedia reader can't render anyways.) IIRC pure text is only like 2 GB.
There is a torrent for them somewhere.
As large as that is, I am surprised that it wasn't huger than that.