Cancel Running Snapshot
It did take a little while to cancel the job (during which time I clicked the Cancel button repeatedly wondering if it worked), but it did work (without deleting my older snapshot from 4 days ago):
snapshot 2009-04-07 21:42:44 2009-04-07 21:43:31 47 seconds userAborted
Again very minor, but it would be reassuring to show it as canceled immediately (–cancel pending--) and asynchronously cancel the snapshot job