Yes, but they are either desktop style or mini-tower style. The Aria, Fragbox2, and Hornet are your choices for cube style. There are some Japanese made cube cases that fit mATX but the price to purchase and ship to the USA is astronomical.
Theres a bunch of mATX cases, but none of them have the 'shoebox' style like the fragbox, shuttle, and aria. the rest are either HTPC horizontal chassis or vertical dell style chassis.
See this thread and post #11: http://www.hardforum.com/showthread.php?t=874876&page=1&pp=20
Think I have most of them listed there. There's another Chenming case I saw the other day, but it's pretty much like the Hornet and doesn't even support a full-sized ATX PSU.