Very few packages show information in GSlapt's "Changelog" tab. Often, a workaround is to visit the Website listed under the Description tab to find out what's going on.
Lack of information in the ChangeLog tab is mainly my fault - I never know the best format, and I'm usually in a hurry, given the amount of time repo maintenance takes. Even if there was, all it would say is something like 'updated - latest version'.
I visited the URL listed for gslapt, and all it said was "updated to slapt-get-0.10.2g API". So it was slapt-get that had reason to change, the new gslapt needed only to match. From slapt-get's site (same page, previous paragraph):
0.10.2g Sept 27, 2010
* api cleanup, typedef'd old structs
* updated el translation from George Vlahavas
* updated pt_TR translation from Sérgio Surkam
* updated fr translation from Verachten Bruno
* updated es translation, new es_AR translation from Fernando Velo
* added slapt_download_data to public API
* translation changes by Igor Murzov
So, mainly, "api cleanup" in slapt-get. Might work faster, but it's not listed as a bug. I'm going to grab it 'cause I like to test, but don't see a need to install this one otherwise --- at least until a few favorable replies are posted.
Most packages will include a ChangeLog, which should be in /usr/doc/<package-name>-<package-version>. That normally contains far more information than the ChangeLog entry that would be used by Gslapt.