Currently Being ModeratedAug 21, 2011 3:46 PM (in response to Syth)
I don't think that is supported, but it might be possible to override and use it anyway.
When you mount the shared folder on your MacBook Pro, open the Backups folder. In the Titlebar of that window, drag the little folder icon to the Devices section of the Sidebar. Now, see if Time Machine sees it.
Currently Being ModeratedAug 22, 2011 7:49 PM (in response to Barney-15E)
Well, it certainly was supported. here's a random technote:
"If you use Time Machine with a network backup volume (such as a Time Capsule disk or an AFP share from another computer) in Mac OS X 10.5.3 or later,"
Currently Being ModeratedAug 23, 2011 4:29 AM (in response to Syth)
I believe that was the original plan, but when they found they couldn't control error-checking to the extent they needed for Time Machine, they changed the requirements to this:
Setting up Time Machine is as easy as connecting an external hard drive to your Mac via FireWire or USB, or by connecting to a Time Capsule. You can also use a secondary internal disk if your desktop Mac has one (that is, a disk that you don't start up from).
It does go on to state this, which seems contradictory:
If your backup disk is on a network, the network server must use Apple File Protocol (AFP) file sharing and both your computer and the networked backup disk should have Mac OS X 10.5.6 or later installed.
But, I think that just implies that it was a choice from the first blurb, and is on a network.