An AGPL version of BitBucket could be a very interesting prospect. Atlassian have stated explicitly that BitBucket will always be SaaS only, so subscribing there will always be about the hosting, rather than the software itself.
The Enterprise version is called Atlassian Stash, and that has a bunch of features BitBucket doesn't need, but could potentially be very useful in a corporate environment (like selective publication of repos outside the firewall).