People are odd creatures. Sometimes people want to see why different packages need to be updated and want more information about what the update will achieve.
The pk-updates application will list updates and show more information if you click on an entry. There is no such information from yum yet (AFAICT), but I'm trying to design the signal to be powerful enough for the other backends and for yum when it gets that data.
If you click close, the application will close. If you click apply, then the application will close, and the update will continue in the background. Yay for async.
If anyone wants to fix any of the applications to match the GNOME HIG (or other spelling or grammar fixes), send me an email and I'll get you commit on my internal development server; I'm really no good at that sort of stuff. Thanks.