While, in my opinion, there are some things worth waiting for, (like Mac Pro!!), waiting for Leopard is silly. It's just an OS update, and won't be revolutionary. If your a student, you'll be able to snag a copy for considerably less (~$80). Go for it now.
On the otherhand, it may be worthwhile to wait until Apple resolves the Rev A bug with their current line of Macbooks. Many owners are reporting the same problems and appear to have faulty machines.
At the end of the day, the decision is yours. Whatever you do end up getting, I'm sure you'll enjoy it.