camel@d830:~$ cat vboxgroupsnap.py 
#!/usr/bin/python

from vboxapi import VirtualBoxManager
mgr = VirtualBoxManager(None, None)
vbox = mgr.vbox

for m in mgr.getArray(vbox, 'machines'):
	print "Machine '%s' belongs to groups:" %(m.name)
	for g in m.getArray(m.name, 'groups'):
		print "'%s'" %(g)

camel@d830:~$ python vboxgroupsnap.py 
Machine 'OLDIE' belongs to groups:
Traceback (most recent call last):
  File "vboxgroupsnap.py", line 9, in <module>
    for g in m.getArray(m.name, 'groups'):
  File "/opt/VirtualBox/sdk/bindings/xpcom/python/xpcom/client/__init__.py", line 384, in __getattr__
    raise AttributeError, "XPCOM component '%s' has no attribute '%s'" % (self._object_name_, attr)
AttributeError: XPCOM component '<unknown>' has no attribute 'getArray'