is the processor replaceable?

I am interested in buying the new 20" aluminum iMac with the 2.4GHz processor, but I'd like to replace the processor with this one: Newegg.com - Intel Core 2 Duo E8600 Wolfdale 3.33GHz 6MB L2 Cache LGA 775 65W Dual-Core Processor - Processors - Desktops
Is this possible? Some people are saying that the CPU is soldered down, others say it's possible. Has anyone actually done this?

The CPU in the iMac is not a user replaceable part.

Just look at a iMac,...Apple just does NOT make computers and laptops that are meant to be opened and "messed" with. Now, why don't you just update the RAM? It is inexpensive, VERY easy and a good idea if you are stuck on the entire processor thing.

I tried to install just a new lid on my MacBook and almost ruined the darn thing!

Your link is for a desktop CPU. The heatsink won't even fit in the case.

While the processors used in the existing iMacs largely resemble those of Intel's current Montevina-based offerings, they're actually a special run of the chipmaker's Santa Rosa-based offerings developed at Apple's request. They operate at high clock speeds and support a faster 1066MHz bus versus the 800MHz of the Santa Rosa-based parts that were available to the broader market at the time.

So to answer your question, it will not work.

Upgrade Your iMac to a Core 2 Duo Processor | Mac|Life

AMFITEATAR - Upgrade your iMac 20" or iMac 24" aluminum 2007 & 2008 to 1.5TB Hard Drive and 4 GB RAM - DIY Guide

Good luck dude, your gonna need it!!