There are several programs to get mail notifications in the notification tray in KDE 4 but up until now there have been no native KDE ones: cgmail, and gnubiff rely alot on Gnome. There is the emailnotify plasmoid which isn’t too shabby but I wanted my notifications in the notification area!
Popular KDE 3 applications are making their way gradually to KDE 4 and kcheckgmail just made that plunge. So thanks to the devs that got this done.
Kcheckgmail for KDE 4 would still be considered beta software though as I encountered a couple bugs setting it up. After setup though kcheckgmail has been running good the last few days.
For now if you want to use kcheckgmail you’ll have to compile it from git. Luis has the basic instructions on how to do this.