MS Vista BitLocker - volume or drive?

[spencerforhire <spencerforhire () gmail com>]

I have seen some confusing statements regarding MS Vista's BitLocker
feature.  Some say it supports "full drive encryption" and others say
it only supports encrypting the operating system volume.  For those of
you running Vista and using this feature, what has your experience
been?  Browsing through TechNet, I've seen both of these statements
made which isn't helpful.  ;)

One of the things I want to confirm is whether BitLocker would encrypt
additional volumes (e.g. if I have two volumes on my laptop, one for
the OS/apps and another for data) or allow me to encrypt the entire
drive even if I'm running multiple operating systems, e.g. Vista and
OS X on the MacBook Pro.