Eric Böhnisch-Volkmann, writing for the Devonian Times (the DEVONtechnolgies blog):
Sychronization via iCloud was the no. 1 feature request on our list. And here we go: DEVONthink 2.10 and DEVONthink To Go 2.6 let you keep your databases in sync via iCloud and without entering anything except for the optional encryption password. No messing around with sync store names, server addresses, or login credentials. Add the iCloud sync location, check off the databases you want to sync, done. It can’t be any easier.
This is the feature in this update that will get most people excited, assuming they have enough iCloud space. But some of the other features, such as improvements to syncing on both platforms, are just as important. There’s a pretty good list here, so check out the full post.