I agree, get a subscription to some mags. (BIKE MAGS!)
It just takes alot of time looking at bikes and reading about them, talking to people about them, etc to be able to discern different bikes. Just like cars. However, with bikes, it is alot harder, and very different for cars. Since bikes are more performance oriented, the designs are typically closer than are cars. Crotch rockets look similar, dirt bikes look almost identical. It just takes experience. For example, gsxrs have a kind of diamond shaped, single headlight, rather than the dual 'eyes' kind of look. a bike with an undertail exhaust may be a cbr, if it is stock. You can always tell a KTM by the angles. Ducatis and Buells have very distinct looks.You should definately be able to pick a Busa out of a crowd. Its all in being familiar with all the various shapes and angles that the manufacturers put into their bikes. With dirtbikes, sometimes it is as easy as looking at the color. However, motorcycles are very widely customized. There are alot of custom bikes, so once you seem to think you have it down as far as stock bikes go, you see a custom, and may be confounded.