Just a quick write up of my experience with the new 27" LCD compare to the old 30" ACD. Not sure if its too late but hopefully it will help someone.
Went to the Apple store, had the 30" ACD and 27" ACD side by side, spend about 20 min compare them side by side, doing pretty much the same thing and this is what I found.
The nice thing I like about testing at Apple store is they have the same demo material to test on every station, same iphoto pics for example so its easy to do a side by side comparison. This is not a super technical side by side comparison though.
The 27 is definitely has much nicer display quality, color, contrast, finer pixels.. just everything, its a more modern, better quality monitor. Things pop out much more and the colors are sharp and great contrast. And very nice details in the same pics. Some things are settle, but you can see the difference, like the way it displays black colors, settle things I don't see as clear on the 30 that I see more clear on the 27. Glare can be annoying to be honest, but I might be willing to overlook it with all the things you do get with this monitor...
However... I won't buy the 27 though. And the main reason is the size of the screen. After even just this 20 min + of usage, I do find having the extra resolution and screen space does make a big difference (at least to me) for having such a big screen in the first place. You basically lose a big bottom chunk of screen real estate and when you have a few apps up, it does make a big difference. So unfortunately, I would of love to get something like the 27. So I am probably going to get the HP ZR30w instead.. Maybe Apple will come out with a new 32" ACD?? 😀