I have accurately calibrated my display, so yes the colors are accurate on my glossy display. The pictures, however, show that the antiglare seems to have less backlight, more blur, whiter blacks, and other typical matte disadvantages. The antiglare also seems to have a yellowish tint, which shows the colors aren't as accurate as the glossy.
Also, if you look closely, more detail can be seen on the glossy than the antiglare.
UMBP Glossy Hi-res seems to be of a better quality than the 1440x900 cruddy small screen. It seems to have better color quality, which IMHO surpasses the antiglare by a long shot.
Seriously, with a screen as bright as the glossy, does the glare really bother you enough to shell out another $50-150 on an antiglare screen? I'm using a glossy screen right now and I can barely see any reflections. Save your money, keep the glossy display, and buy some extra RAM or even optibay an SSD.