They aerated the greens today at my course (just got membership last week.) How long will it before they are back to normal?

It really depends on a few factors. But my course, which is bent grass greens, take about 3-4 weeks before they are totally back to normal. But I am sure that changes depending on grass and climate.

Like pingman said, it depends on the course, but I know at the course I work at the (not-so-great) greens are usually back to normal within 2 weeks, usually 10 days.

depends on the ammount of rain and the type of grass... In Miami most courses hit the greens three times over the summer (sucks)... However, it is rainy season so they usually come back somewhat fast (yay), never fast enough though(boo)...