doesn't feel like glass at all... probably more like plexiglass.
either way, glass cleaner should be fine in small quantities. do not apply the liquid to the computer directly. first spray on a cloth, and then wipe with the cloth.
We have monitor wipes (
like these) at work that i use if i need heavy-duty grime cleaned off of electronics. They're saturated in a non-alcohol electronics-friendly solution. They work very well, and you should be able to find them at any store that sells computers. There is also a product called "iKlear" that is highly regarded in the Apple community... never tried it myself.