As you are probably aware, PCLinuxOS is a rolling release therefore if you have an updated 2010.1 setup it will be the same as if you had just installed the 2010.11 version (after the 2010.11 was updated of course

)
I believe the release schedules of approx 3months between each release is so that new users (or new installs) don't have to download/update a ton of updates (I would imagine if a 2010.1 update was done today it would probably need a 600/700MB download)
The biggest change is probably the KDE 4.5 release updates.