Fudzilla has found a german rumour purportedly giving details about the GT212:

The higher transistor count (due to increased number of SPE's) along with probably higher clocks will tend to offset the power savings one could expect from the geometry shrink and smaller chip surface area; and going to a 256b memory bus - even with GDDR5 - is likely to result in lower memory bandwidth, unless the GDDR5 used is twice as fast as GDDR3.