Well, it depends.
The composition of the glass, the thickness (depending on the type), and any coatings (i.e., "low e"), etc., can all affect the transmission properties and abilities of the glass.
The size of the window and the proximity of the AP/antenna to the frame of the window (and the composition of the frame) might also have some influence.
Chances are good you'll be OK, but like with anything wireless, there's no guarantees until you prove it with physical resources (i.e., like a site survey or "just doing it").
A real good "rule of thumb" is "Don't promise anything until you've tried it."
Good Luck
Scott