Ah, ok. That wasn't really a problem. I don't remember the details, because I joined the N900 and Easy Debian comunity quite late, but it was essentially just a matter of doing a proper dist-upgrade to Squeeze.
It's not an issue with any of my images.

In the Wheezy images you can run upgrades as you would on a regular Debian system.

In the Jessie images it's gotten more complicated again, because I had to patch and recompile glibc to work with Maemo's old kernel. And it has to be done for every new glibc update.
In this post [1] I linked an archive with the latest glibc packages, but I just realized the link is down again. I'll re-upload it some time later this week.


[1] http://talk.maemo.org/showpost.php?p...postcount=3219