Yes, the 2100+ is a 1.73GHz AthlonXP on the .18u Palomino core. It is scheduled for release within 3 weeks. This will be the final member of the Palomino core (.18u) family.
The first Thoroughbred is likely to be a 2200+ (1.8GHz) on the .13u core. I am told it will not feature 512K L2, nor will there be any changes from Palomino. Some have said that AMD has quoted "a couple insignificant" changes, but I've not been able to confirm that.