That is correct Pix, it is 0°, 45°, 90°, 135°. Not really sure what the applications are in 2G and 3G network- maybe applicable for 4-way diversity (?) that many vendors these days offer. I am almost sure Andrew has these antennas.
Also, I think these antennas could be used in 4G technologies like WiMAX for 4×2 MIMO where TX at the Base station transmits on 4 parallel paths. Its also true that 4G will extensively use “smart antennas” which is an add-on smart functionality over X-pol antennas.