There are very few phones running ICS and even fewer that have this smaller screen size. The high end android handsets pretty much all have larger screens and these are the ones that receive the updates.
The only phone I can think of that fits your bill completely is the HTC One V (3.7") however I would personally take the HTC One S. Although it is slightly larger than you would like at 4.3" it is markedly better in all departments including aesthetics
Edit: Ah, there is also the Sony Xperia P which has a 4" screen and should be upgraded to ICS in Q2 2012