I looked more closely into this issue, and found more infos at http://packages.qa.debian.org/u/uqm.html : they have 0.6.2.dfsg-4 as the latest version, but under "testing" or "unstable".
I.e. you get the new version only if you have set up your system accordingly, or you request a specific version by hand.
Debian stable tends not to update very often, so people playing games (like UQM) usually need to grab the package from testing. As was mentioned above, submitting a request the the package maintainer can help keep the Debian packages up to date.