Being a student he might not be able to wait since school is starting up now.
I have had a few friends ask me this same question.
You have too look a what you will gain and loose by buying now or waiting till october. Here is the MR link to buyers guide and explains on average when an update should happen. According to the average on here it should be about 4 months.
https://buyersguide.macrumors.com//
If you buy now, you can get a free ($100) printer, a free ($200) iPod, $110 off Apple care, the ability to have a laptop at school, and the satisfaction of having it NOW.
But if you buy now you loose out on a free copy of leopard ($69- look above at user leehro post), and also have the possibility of there being a new update.
If you wait till leopard to buy then you get Leopard for free ($69) and the possibility that if there is a update you will have the latest and greatest.
But if you wait to buy you loose out on $410 of freebies (printer, iPod, Apple Care), the satisfaction of having it NOW, and the simplicity of having a laptop at school.
This all holds under the fact you would take the free iPod, Printer, and discount on Apple care. as well as you don't have a computer to use at school right now.
Financially it would be more intelligent to buy now to get the freebies you can easily pawn off to other college students and get the good discount on Apple care if you like it. (If Apple care is always offered at a student discount , please someone correct me) You will have to spend $69 later, but you will get $410 in freebies now and that great satisfaction of actually having the new computer NOW. Obviously you will not sell those two things for resale but I just sold my free Nano for $150 and the printer for $75, so if you are looking down the "pawn it off" lane then you will still get $225 dollars cash to put towards Leopard and beer money (Dorms, gotta love em) and $110 off Apple care.
Now about the update, I just do not find likely, but with Apple that is always possible. And please ignore any posters on any forum that says they know a release date of any Apple product before it is publicly announce, because they don't.
Good luck, hope you pick one up, and I know you will love it!