For those tracking "testing" which has now passed from Lenny to Squeeze, there is a problem that has struck a few people (including my girlfriend). This may be limited to laptops but I'm not sure of that. It doesn't effect all systems (mine for example ). The keyboard basically stops working normally in X after the upgrade. Every 2nd keystroke is treated like a cntrl or scroll-lock type stroke regardless of what key you really hit. The culprit in this story appears to be the xkb-data version 1.5-2 package. If you encounter this problem, removing this package and replacing it with the xkb-data-legacy package (it is usually done automatically when you remove xkd-data). It has already been posted as bug #514975 on the debian site.
Cheers,
jdk

Thanks for the heads up. I've not experienced the problem myself (probably because I am running Debian on a desktop), but I am sure others will find this useful.

Yeah, as I said I'm in your position (running desktop) but it's a scary problem if it happens to you. Very hard to diagnose too.
Cheers,
jdk