The last four phones to get Android Jelly Bean are Xperia S, SL, ion and acro S. The rollout for them will begin a few weeks after the second batch of phones get the Jelly Bean.
Here`s the quote about the Xperia U, sola, miro and tipo:
"The quality of Xperia's software experience is dependent on a number of factors including: screen resolution, hardware platform and RAM. In the case of Xperia go, this combination came together in a way that meant the user experience running JB was not adversely affected.
Unfortunately, in the case of Xperia tipo, Xperia miro, Xperia U and Xperia sola this wasn’t the case – so we made the decision to keep them on Ice Cream Sandwich."
This one is about the arc S:
"Xperia Arc S is part of our 2011 portfolio, which won’t be upgraded beyond ICS. The reason being – user experience is at the heart of our product development and support; after thorough evaluation, we concluded that the user experience for our 2011 Xperia smartphones will be superior if they remain on Ice Cream Sandwich versus being upgraded to Jelly Bean."