There are rumors and other indications that Apple will be releasing upgraded Macs and iPods in late September. So if you're thinking about getting one but you don't need it just yet, you might want to consider waiting a month.
Of course, there will always be something newer and better coming along in a few months; if you need something now, and/or the currently available products do everything you want, then of course you should go ahead and buy now.
If you're trying to decide, here's some potentially useful info from the MacRumors Mac Buyer's Guide (not affiliated with Apple):
- There are rumors that Apple will upgrade the iPod Touch and MacBook in September. (There've specifically been rumors that the new MacBook will feature a silver/chrome look like the MacBook Air and MacBook Pro, so if you like the current black or white plastic look, this might be a reason to buy before the update. Unless the rumors are wrong, of course.)
- The iPod classic has never gone more than a year without an update. The last two updates were in September 2006 and September 2007. Similarly with the iPod nano. (Hard to say about the iPod Touch; there've only been two releases so far, so who knows what the pattern will be over time. The iPod shuffle seems to be on a shorter release cycle; by a month from now, it'll be at nearly its average release-cycle length.)
- The Mac mini has never before gone more than 11 months without an update; it's now at over twelve months, and counting. There've been rumors for over a year that the product's being discontinued. Hard to tell.
- The Mac Pro is probably somewhere near the end of its update cycle, but hard to tell. It has sometimes gone ten months without an update in the past, so the next update might not come 'til November or so.
- The MacBook and MacBook Pro were last updated in February, but iIrc, that was a relatively minor update that was seen by the rumor sites as likely to be an interim placeholder (because of then-forthcoming new Intel chips).
- Finally, the MacBook Air was first released in mid-January, and there've been no updates. Neither the MacBook nor the MacBook Pro has ever gone more than ten months without an update, and more than eight months without an update has been quite rare. So although I've seen no rumors or even speculations that the Air will be updated next month, it seems quite likely to me that there'll be a new Air model by November at the very latest, and probably in September.
Of course, sometimes these "updates" are just small increases in processor speed, which may not be worth waiting for. But sometimes they're complete overhauls of the whole internal and/or external design.
And of course I'm jumping to conclusions based on past update-cycle length; past performance is no guarantee of future performance. But over the past six years, there've been eleven updates each of the MacBook and MacBook Pro, and only two of those releases have been more than nine months after the preceding ones, so Apple has been pretty consistent in its laptop update cycle for quite a while.
Still, a reminder is in order: when the Buyer's Guide says "Don't Buy--Updates soon," that only means that it's been longer than average since the last update; it's no guarantee that there'll actually be updates soon.
And all this info puts educational customers in a bit of a bind. For example, if you're a student, faculty, or staff member at a school, and you buy a new Mac before September 15, Apple will give you a free (well, 100% rebate) iPod Touch or iPod Nano. So there are incentives to buy sooner rather than later.