Looks like the final nail has been put in the 2.0 branch, as the WordPress blog lets us know that it has been marked as deprecated.
The WordPress team had initially committed to maintaining the WordPress 2.0.x legacy branch until 2010. Unfortunately, we bit off more than we could chew-the 2.0.x branch is now retired and deprecated, a few months shy of 2010.
The reasons for this are simple: current security fixes would require complete re-writes of major features and functions within the branch, eating up precious time that could be better spent elsewhere.
With the 2010 end date less than half a year away, I doubt many people still relying on the branch are going to cry foul, especially with the modern upgrades to the user interface, management of plugins and themes, as well as a variety of other simple tweaks that have made WordPress much easier to use.
If you are still using the 2.0 branch, it is time to get with the times.