Most of the packages from the EmacsWiki are being mirrored just like packages distributed elsewhere. A few have have been left out for various reasons.
The respective repositories on the mirror contain the full history beginning with the 30th August 2009 though the commit messages are just timestamps. Since the 20th November 2011 are potentially meaningful.
You might also be interested in the Git repository which mirrors all pages and files from the Emacswiki.
You can contribute to the mirror by reporting new packages.
If you maintain some packages yourself please check if the most recent versions are being mirrored. (Some packages have been imported manually because I could not find upstream. In this case new versions won’t be mirrored automatically.) Otherwise inform me where they can be found.
Of course you don’t actually need to be it’s maintainer to report where some missing package can be found.
Maybe githubs ‘gist’ could be used to host many of the elisp snippets found here on emacswiki? --CH
I agree this would be nice. But it is unlikely to happen because many of the most active Emacswiki contributers don’t use git regularly and have likely never used github. (How can I tell? Well they are not fans, so…). In any regard, if you want gist integration the only way to make it happen is to start working on it yourself. If we had a nice implementation then people might actually like it - otherwise it will be hard to convince anybody. – JonasBernoulli