I bought a Pleo a few months ago.  My kids are fascinated by it.  They enjoy petting and feeding it.  The Pleo is a cute little robot, sorry... I mean, artificial lifeform.  Don't expect it to play fetch and run around like a dog though.  The motors can only go so fast moving his limbs.  I've found that after prolonged movement, his battery gets hot.  Which is actually rather interesting because then it feels as though he has a body temperature.

My 1 year old daughter is particularly fascinated with it right now.  She cries if I have him sitting on a shelf because she wants to play with him.  She also cries if he is turned off and not amusing her.  My wife and I laugh watching her react to him.  I think she is going to have these childhood memories of playing with a dinosaur, which could be really interesting as she gets older.  If she becomes a paleontologist, we'll know why...  Of course, if she becomes a roboticist, then that'd be cool too...

The people at UGOBE are working on a PDK (Pleo Dev Kit).  They have been working on that for some time.  I'm looking forward to getting my hands on it cuz I'd like to see what I could do using .NET.  However they seem to be taking a long time getting the PDK out to the public.  Right now we can use their scripting interface to write stuff for Pleo.