Definitely past the point of no return for me now.
If you have a decently functioning computer right now I'd recommend to wait for Apple's 32nm Arrandale offerings.
Intel don't often majorly upgrade their mobile architecture - around once every two years, so I don't think it that prudent to get a 45nm Penryn at this end stage of the cycle. That's a 30% reduction in process size, I imagine with similarly proportioned reductions in power and heat.
It'll likely make a big difference to any updated MBA/MBP.
Getting an Arrandale Mac early next year would be the perfect timing as I see it. That is, unless it's an Arrandale in a completely new form of Mac Rev A, in which case some say it's best to wait until an ironed-out rev B comes along (eg MBA), but this isn't a strict truism (if you pardon the oxymoron).