Time Capsule Q

Multiple computers can be backed up using Time Capsule but I'm not sure whether computers that don't back up to Time Capsule will be able to use it.

I'd like one as well but I'm going to let the early adopters identify the kinks first. Once they're released, I'm sure we'll all have the answers to our questions.

I expect that users will not be able to access the the Time Machine backups from other computers made on your Time Capsule.
My rationale: I have three user accounts on my MBP. Time machine makes backups of all three at once, but I'm only able to access the backups for currently active user account.

Suggestion: create a sharing folder on the TC hard drive that can be accessed by every computer with which you want to have share. Anything you need to share can be stored in that folder.

It depends on how you setup access to the disk. You have choices of using the Time Capsule password, a disk password, or a user account password. It's just a shared network drive, so it will work the same as if you shared a drive off another Leopard machine.