You can clone with
HTTPS or Subversion.
It would be awesome if y'all would tag and/or branch stable releases. Apart from the benefits it would have for developers working on ack.vim (like, being able to easily check out the code that people are ostensibly using on their machines, for instance), it would also be a boon to those of us using pathogen to manage vim plugins. We could submodule the "stable" branch (or whatever you want to call it) and then just always have the latest stable branch. Right now the choice is between manually managing it with the .tar.gz from vim.org or getting potentially unstable code.
Thank's for the issue, and sorry about the late. I started to release this with tags, at now we are on 0.9 and have some goals to 1.0.
Awesome. Thanks! Better late than never!