Hi
I am planning to buy Broken Sword 2, is it possible to run the gog.com version on a macbook with scummVM?

Yes, the GoG version is the standard ScummVM version... however you might have problems actually getting to the needed files, as the installer is Windows-only. But if you can get a friend to run the installer for you and give you the resulting files, it will work.

Adding to what hansschmucker wrote, you could run the installer using WINE if you don't have VMware or similar installed, and you could also run the game through wine if you didn't want to bother setting it up in ScummVM, but I haven't really tested running it that way beyond seeing if it actually worked. Also you may need to manually specify the Extras folder when setting up the game in ScummVM.
With the default WINE setup the files will end up in "~/.wine/drive_c/Program Files/GOG.com/Broken Sword II" or similar.
See http://wiki.winehq.org/MacOSX/Installing for some info if you need it, and make sure you grab Xquartz from http://xquartz.macosforge.org/trac/. I've found the Darwine install from http://www.kronenberg.org/darwine/ to usually be better than the other one.

Thanks guys!
I have bought the game now, works like a charm. I have a desktop computer with windows for gaming, but it is nice to have a game-to-go too. And Broken Sword is perfect.