Sony phones seem to all follow the Xperia S model which intially was the LT26i and got unvieled at C.E.S. The Sony SD25i Kumquat was seen last month and, a couple of days later, documents revealed that it might wear the Xperia U name.
However, we didn't see the two Xperia phones side-by-side, that is,
until now. In the image above (and lots more at the source link below)
you can see the 3.5-inch Xperia U compared to the Xperia S from several
angles. At a first glance, the Xperia U seems to be a smaller version of
the Xperia S, with a removable battery though. It is expected to pack a
1GHz dual-core processor and a five-megapixel camera, aside from the
3.5-inch FWVGA screen.
While looking at the pictures we can now tell you for sure that the backplate we have recentley seen that for an upcoming Sony device -- is indeed the battery cover of the Xperia U pictured below