Usually the cages that are side by side have a visual divider of some sort up, because the sight of other chameleons can really freak some animals out. The glass is not an issue in this case, because it can centainly make regulating temps and humidity much easier especially if you live up north - BUT, since it's an aquarium it doesn't provide a lot of ventillation, unlike special made vivariums do. So if they're really young I think it's ok, but not for the long-term. Also, because they are male and female, he will be ready to breed long before she is, and will probably dedicate a chunk of his day to trying to woo her through the screen, and she will be annoyed and stressed. Or, worse, she may be pushed into producing eggs earlier from the sight of him, and that can be really tough on a young female.
Most importantly, however, is keeping her temperatures cooler than his if you want her to not produce infertile eggs for a while. This is an excellent blog to read:
http://raisingkittytheveiledchameleon.blogspot.com/2007/12/keeping-female-veiled.html If you keep her cooler and on a strict diet she will live longer without producing any/as many eggs in her lifetime. You'd want to start this technique at about 5.5 months, so you don't have to change anything yet, but keep that in mind.
So basically, I would scrap the idea if I were in your shoes. It's easier to get them both their own enclosures and set those up. It doesn't take too long to ensure that the bulbs are putting out the proper heat and to get a misting schedule that maintains humidity in the right range.
