I can't legally comment on Leopard features because I'm an Apple developer and have signed a non-disclosure agreement.
However, from the information that Apple has made public about Time Machine I can make two comparisons.
First, QRecall is vastly more efficient than Time Machine (and most other backup applications in general). Time Machine simply copies files, while QRecall analyses the data in files and eliminates any duplicate data from the backup archive. So your backup storage is guaranteed to be larger than the original set of files with Time Machine, while with QRecall your backup archive plus incrementals will more than likely be smaller. This means that you can use a significantly smaller backup drive or keep incremental data longer, or both.
QRecall is significantly more configurable than Time Machine.
Personally, I was both delighted and dismayed when Apple announced Time Machine. Delighted, because Apple recognized many of the same problems with existing backup software that QRecall is trying to overcome. I think it will also encourage more people to implement a disk-to-disk backup plans.
At the same time it's disheartening to see Apple integrate many of the features that we've been developing over the past two year then build it into the OS and give it away for free.
But QRecall still has a distinct set of features that I think will provide some competition to Time Machine.