Novell has released an FTF (Field Test File, aka Beta version) of GroupWise PDA Connect that works with WM5.
http://support.novell.com/filefinder/20641/beta.html
On the page above, look for "FTF: PDA Connect Update Multilingual." This version supports WM5, and works with GW 6.5 and 7 SP1.
I found out about this prerelease version by browsing the Novell support forums:
http://support.novell.com/forums/2gw.html
Near the bottom of this page, click on the HTTP link beside PDA Connect.