Today, Ask Jeeves announced an upgrade to MyJeeves named MyJeeves 1.2. The two main differences are (1) Tagging and (2) Photo Management. The big one obviously is the tagging component.
Read how they explained the use of tagging in MyJeeves 1.2:
The first impulse was to blur the line between foldering and tagging by merging them into topics. This turned out to be too confusing for most people. The second scenario was to overlay tagging on top of foldering, resulting in "virtual folders". This is the approach Longhorn seems to be taking - sorry, I meant Vista...which sounds far less intimidating - and dagnabit if it didn't work. So there you have it: "tags as virtual folders" is what we just launched with MyJeeves 1.2.
"Virtual folders", in reality, that is what it is.
I have started threads about this at Cre8asite Forums & Search Engine Watch Forums.
Update: Tagging has been around for a while now, not sure why they blogged about it today. Gary notes that he blogged about Ask Jeeves adding tagging on April 11, 2005.