There aren't many other details in these types of files, except that the screen resolution will be 480x854, and the ScreenSizeChar is 44x32, which hopefully will be slapped on a larger display. The phone should be capacitive touchscreen-only, since the ones with a physical keyboard SE marks with a "K" in the internal codename. Moreover, under the keyboard section in the file below we have "phone keypad" listed.
Also, considering that MT15i is the Xperia Neo, MT11i might fill in the gap between the smaller 3" screens on the Xperia active and Xperia mini and the 3.7" one on the Neo, or even the 4.2" on the Xperia arc, which is LT15i. The "M" in the codenames obviously stands for middle, while "L" might mean large, and "S" small, judging from the screen sizes of the actual handsets behind the SE codenames.
A relative disappointment is the ARM Cortex-A8 processor listed, which means we will have yet another single core 1GHz phone from SE, but we know the big guns are reserved for the Sony Ericsson Xperia duo, so no complaints.
Some specs actually coincide with the Sony Ericsson Xperia ray, which we previewed not long ago, and found out to be a very promising little Android handset. The Xperia ray, which, however, goes under the ST18i codename, so the MT11i is one more thing to look forward to from Sony Ericsson in the third quarter of this year.
source: SonyEricsson via IT168 (translated)