This is the Wikipedia dump of all articles (as of Jan-2012) in the ZIM format, no pictures though. Use Kiwix to read the contents in the ZIM file.
Kiwix is an offline reader for Web content. It\'s especially intended to make Wikipedia available offline. This is done by reading the content of the project stored in a file format ZIM, a high compressed open format with additional meta-data.http://www.kiwix.org/