In fact, the architecture is exactly the same. These new products all have 40nm graphics chips with support for DirectX 10.1 -- just with optimized performance or power consumption levels. The flagship GTS 360M, for example, sports the same number of cores (96), the same 128-bit bus width and support for GDDR5 memory clocked up to 2GHz as the GTS 260M, but is capable of processing slightly more gigaflops (413 versus 396).
The GT 335M makes the largest leap in performance of the entire series with 72 cores and up to 1,066MHz DDR3 memory. Below it, the GT 330M and GT 325M have the same 48 cores as Nvidia's previous mid range models and are primarily clock speed boosts compared the older GT 240M. The company is yet to fill the enthusiast segment, so we'll have to wait and see if a GTX 280M/260M rebadge is in order or they are holding out for Fermi.