Actually I 'm in the market for a new iMac for my wife. She likes my new 17 MacBook Pro, especially since I upgraded the CPU and maxed the RAM. I was on Apples site yesterday and priced them out and it was the same models, 20 inch, and a couple 24 inch models.
Today, the new iMac came out. Now you have a choice between 21 and 27 inch models, and the top 27 inch has an i5 quad core processor. So, with a new model out and the price actually dropped a little, NOW NOW NOW is the time to buy. I'll be placing my order for her computer in about a month.
The new 27" iMac with the i5 quad core CPU is only $1900.00 for student on the education discount page of the Apple Store site.
The general consensus is that you should always wait until Apple does an event in January. Since they won't be at Macworld anymore, their "secret" event should reveal all in Late January! If I was buying, I would wait... but since I got a MacBook Pro as a gift over the holidays, I am happy I have it.