An idle trawl through Time Machine tech.

> http://www.macworld.com/article/132118/2008/02/timemachine1.html <
> http://www.flickr.com/groups/macintosh/discuss/72157603284372963/ <.
In some depth (read right through):
> http://arstechnica.com/apple/reviews/2007/10/mac-os-x-10-5.ars/14 < and
> http://web.me.com/pondini/Time_Machine/Works.html <
which explain Unix hard links, symbolic links, soft links and why these aren't aliases. Note the warning at the bottom of the latter URL.
Apart from Apple's own, revamped, discussion pages,
> http://support.apple.com/kb/index?page=search&product=&q=time%20machine <
there is some Q & A stuff is at superuser.com (see the "related" column),
> http://superuser.com/questions/33503/are-time-machine-backups-incremental-and-is-time-machine-any-better-on-snow-leop <
Enjoy!