There is an option, in system tree view, to export tree structure.
However, this only appears to give you the group structure, and none of the sorting rules (eg IP, Tags).
To get to it, go to System Tree, then click the option to view "Group Detail".
On Action menu is an Export Tree Structure, which gives a link to a text file.
Would guess the Import Tree structure option would allow importing from that file.
However, unless someone has some clever (probably SQL related) trick to import the sort criteria, you'll need to put that back in place yourself manually.
Thanks Matt! A bummer though that it doesn't export/import the AD synchronization details