I've released version 0.5.1 of the aptitude package manager (release notes). Once it has been installed into the archive, you can download it from Debian's experimental distribution, or manually from the aptitude package page.
WARNING: This is an unfinished piece of software. Do not install it if you want a package manager that does everything you need perfectly all the time. It is buggy and incomplete.
There are no huge user-visible changes in this release, but there are a number of smaller new features and enhancements. Click through to the release notes to see a list of what changed in this release, with screen-shots.