The sensor in the X-Pro1 will have no low pass filter, like most traditional digital cameras with a Bayer array sensor to remove false colour and reduce moire, and instead, false colour and moire is avoided by using an interesting 6x6 colour filter array. Low pass filters reduces resolution/sharpness of the pictures, so in theory, this sensor should give you sharper pictures than those with low pass filter for the same lens used. Fuji claims this sensor rivals that of the full frame sensors. I guess we will have to wait and see.
The only drawback is the price. At $1700 for the body only, the price is a bit on the high side. When you add a lens, this would be at about $2200, making it one of the most expensive mirrorless cameras around (except the Leica M9, if you count that as an EVIL camera).
2012 will be an exciting year for digital cameras, especially mirrorless. Canon has said that it will introduce a mirrorless camera system this year, in addition to the near APS-C sized sensor Powershot G1X (what's with the X in the camera name anyway?!? Everybody is using it. Does it have magical properties or something?) I hope Canon wont disappoint.
Cactus Flower -- NEX-5N & Zoomar Kilfitt 90mm f2.8 Makro Killar