There's also quite a good article talking about deep stops and gradient factors at:
http://www.gue.com/dplan/docs/Deco/Deep%20Stops.pdf
Something I also found interesting - on a recent trip I was able to compare two computers: a Vytec (with the supposedly conservative Suunto algorithm) and a VR3 (with the 'traditional' Buehlmann algorithm and microbubble/deep stop additions).
The deep stops shown by the VR3 tended to occur on dives where the Suunto went into a decompression dive - doing the 2 min stops (usually between 20 and 30m) brought the Vytec back out of deco mode.
What does it all mean? I don't know, but I have a feeling that deep stops are a good thing!
Regards
Robert