I'd like to setup the ability to have Drupal projects cached locally when I do a Git clone or Drush dl/make, so that if I happen to be offline or just to save bandwidth, when I Git clone/Drush dl/make a project that has previously been downloaded it will pull from the cache instead of from D.o., possibly after pinging D.o to see if there is a newer version (if online).
I'm sure I saw something about this once before, but haven't been able to track down the specifics.
There is a blog post about locally cached git repositories here: http://randyfay.com/node/93
Drush 5 now has a --cache flag which builds up a cache automatically, just as described at http://randyfay.com/node/93.
We have started integrating Drush Make into Drush core and at that time, make will get Drush core's caching features (like what dl and updatecode have).
As the answer was only relevant to the Git, I did a little searching and came across an Issue in D.o. for Drush make that lead to a blog post on how to use Squid to cache Drush dl commands, the blog post is a tad broken due to the Geshi Filter module not running or working correctly, but the information seems like it will be valid. Still trying to wrap my head around it.
