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I think 27" will be released at the same time as the 21", and this is actually the reason both are delayed.

With all the press attention they'll have, it makes more sense for them to sell millions of 21" iMacs to fill pent-up demand as long as people can preorder 27" models.
 
What if you want to up the RAM, gotta special order those online?

No no no. Do not do this. Buying extra RAM from apple = burning money. Get the base amount of RAM, then order RAM from third party. Of course that's assuming the RAM doesn't get soldered in the new model...
 
If the iMac will be available at Apple Stores the day after the keynote, how long is the wait for other retailers (21")? Looking to buy from Best Buy to burn through my rewards points.
 
Still doesn't mean you'll find them in your local Apple store this week, especially outside the US and major cities.
 
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