There's nothing built into Max, AFAIK, to let you copy and past poses on regular bones. But with some of the new features in 7 I wouldn't be surprised if someone comes up with a script to do that. Paul Neale has a script that will let you copy and paste poses for custom attributes, but that's not the same as copying the…
try using the physique tools set created by Anthony Delen - http://www.anthonydelen.com/script_physique.htm You can save out your vert assignments using this script and re-structure your skeleton then import the wieghts back in, providing that bone/biped names stay the same
You can try Anipose. Best described as a pose manager... You can save poses for specific sets of bones and save them out to external files. Don't know if it will work with max 6 and above... http://www.chuggnut.com/scripts/anipose/ver3/Anipose%20install.mzp