It has been a while since the last refresh and if you follow things here, you would have known to wait.
I have an iPad and use iTeleport on my iPhone 4 and iPad to remote access from my home network and remotely into my iMac. Works fairly well. There is some lag but when you need to get some stuff done, it can be quite useful. I wouldn't recommend it for significant workload.
They won't refresh again before Lion, probably not for another year, but they will ship with Lion when it comes out. Lion will cost you whatever it retails for, whether that is $129 or $29 (and I'm guessing it will be back to the $129 as it isn't the minor bump Snow Leopard was), with the only exception being that once they announce a release date (probably at WWDC), any machines purchased after that and before the release will be eligible for a copy of Lion at $9.99 shipping fee, so you aren't discouraged from buying during that 2-8 week period.
Honestly, I've looked at the dimensions and because of the wider aspect, the lack of an aluminum border, and almost edge to edge screen the 27" iMac is not much larger dimensionally than the 24", though the screen is larger of course.
Personally, I am waiting to update my 24" 2.8 Ghz Extreme iMac (aluminum rev. A - Aug 2007) to a new 27" but will hold out a couple extra months for a 10.7 preloaded machine. I prefer to do a clean OS install which I don't want to repeat so soon. Setting up all those apps, and copying in libraries, files, and other data from a backup is something I only want to do once.
Partition your HD with OS and apps on one, your stuff on another. Then it is all easy.... anytime