Two things:

1. If you are running DragonFly 2.7, Matthew Dillon has made some kernel changes, so updating your 2.7 machine will require a full buildworld cycle, not quickworld.
2. The binary packages for 2.6 and 2.7 have been updated to pkgsrc-2010Q2.  This means that pkg_radd will automatically pull down newer packages, and you should make sure your /usr/pkgsrc is using the pkgsrc-2010Q2 release if you want to be sure there’s no version mismatches.

I recently sent out a description of what built for pkgsrc-2010Q2 , though the section on not changing the stable link is no longer true.