The producer of Time Crisis 4 recently talked about the Guncon 3 which comes bundled with the PS3 game. He was asked if it was similar to the Wii sensor bar and said it is basically the same, but the Guncon's 3 LED markers a lot better than the Wii controller, while the Wii has just two LED points, the Guncon 3 has six so it will be a lot more accurate. Moreover he stated that the PS3 will be able to recognize the tilt of the Guncon 3 and its distance from the screen something of which the Wii can not handle.

Is it similar to the sensor bar from the Wii?

Basically it is the same, but Guncon 3's LED markers are actually much more accurate. Much better than Nintendo Wii's controller. In the Wii, there are only two LED points, but for the Guncon 3 there are six LED points, so it is more accurate than the Wii. The PlayStation 3 will be able to recognize the tilt of the Guncon 3, its distance from the monitor, and these things cannot be done with the Wii system.

So the gun has SIXAXIS capabilities as well?

Yes.