I just did a search. Is it this one?
Could it be improved in the future by doing backups at the block-level rather than the file-level? Yes, that would be good for very large files. But in the meantime, this is a great backup system with easy setup, use, and great interface.
Time Machine is great. And no doubt it will only get better in the future.
That's the article. Block-level would be great and let me use it to back up my VMWare virtual hard drives, which I exclude now because it would mean a 10-30 GB backup every time I started a VM. Messing with block-level is a great thing about ZFS and would allow this, but Apple's experiment with ZFS seems to have stalled for some reason.