The official website is here:
(it points to the actual server at http://alleg.sf.net, thanks to Trent for the nice DNS entry)
We use SVN to store the website's source. The repository is here:
The A4 site used a custom source format which made it very hard to update anything - the result was that there was very little maintenance except updating the news section whenever a release was made. Trying some content management systems (mediawiki, moin, drupal, wordpress) it was clear that it's quite hard to find one which does what we want, so the new site uses a custom format again - but this time very simple, and very easy to update.
The source format is described here: https://alleg.svn.sourceforge.net/svnroot/alleg/allegrowww2/proposal.txt
Updating the site
After committing your changes into SVN, log in to the SF shell service, svn update in the checkout directory, then run make:
ssh -t user,firstname.lastname@example.org create cd /home/groups/a/al/alleg/svn_allegrowww2_checkout svn update make
You need to be a developer of the alleg SF project and replace user with your username.