At least with 10.7, it should have since its still the same machine (can't remember how 10.6 handled it). In my experience, the first attempt to use the disk will display a prompt allowing reuse or to wipe and start fresh. Though my setup uses a network disk for Time Machine, which works a little differently.

Bookmarking that site to read later, been wanting to read more in depth on the changes in 10.8. Snapshots now also use the hard drive space in the machine, and get moved over to the Time Machine disk when connected. Really handy to retain the versioning backup aspect if you have the local space.