I just discovered that Synaptic on my Oneiric installation displays about 55 thousand packages instead of 35. About 20 of these have a name ending with
:i386. I also recently read in the Oneiric Beta release notes that the AMD-64-version of has better handling of 32-bit code. I guess these two facts are related. Seamless installation of 32-bit coden on 64-bit installation is explained here.
Are there any optimizations (kernel specific I guess) regarding its execution?