So getting a Mac Pro for my needs may very well be overkill?
The main reason I wanted to wait for the upgraded/refreshed MBP (in addition to the available options I decided I wanted/needed) was that I thought the 45nm 2.6/2.8 ? GHz Penryn MBP would run cooler in relation to the GHz vs the current model. My son has an older, less powerful, MBP and complains of the heat it puts out. I never thought of an iMac (because I was concentrating so much on the MBP). That's another option for me to explore. Thanks.
Without knowing your needs, no one can comment on what you need.
So, here you say...
I do quite a bit of photography and photographic editing and would need precise color reproduction. That was one of the features I was considering in the MBP.....going with a matte high resolution screen for accuracy in color representation.
I need a tremendous amount of RAM because the way I work I keep multiple programs and windows open/running as I bounce back and forth between applications, etc. I really know nothing about the iMac but had assumed it would not meet my needs (and of course, I wanted a desktop replacement that would provide the portability when needed, but wanted the 17" screen due to my 'multitasking' with so many windows open.
If you need precise color reproduction, you need monitor and printer calibration hardware and software. Having a "matte screen" will not give you accurate colors. Having a calibrated monitor and calibrated printer will. This not really a matter of getting a Mac Pro versus an iMac versus a MBP.
As for "tremendous amount of RAM" -- I'd bet you'd be fine with 2GB. My wife does graphic design on a 4-yr old dual G5 system, running 10.5. She could work, albeit inefficiently, with 512 MB of RAM. We just upgraded her to 2 GB and things are great. She's running Adobe CS3, Excel, Mail, and Safari simultaneously. If you want to spent more money, you can upgrade to 4 GB on a MBP or iMac as well. (Just be sure to do the upgrade yourself. Apple charges an excessive premium for RAM.)
Regarding heat: all computers get hot. But only portables sit on your bare legs where you can feel it

My 15" MBP gets really revved up when playing some games. But it's on the desk so I don't care. For living room, on the couch, web-surfing, it doesn't get warm enough to care. Besides, I use a lap desk so it's easier to use and never on bare skin. I consider this a non-issue.
As for portability -- I can't tell how much you want or need it. If this is a real priority, then a Mac Pro or iMac just aren't a solution. But if you want to move your computer about rarely, an iMac is a good solution. They're pretty light and can be transported with minimal fuss.
You can buy what you want. But if you're a teacher with modest income, family to support, and this computer is for personal hobby and modest work uses, you might be better served by getting a good machine (rather than a stupendous machine) and saving $1000+.
Moreover, if you doing typical hobbyist computer stuff, you will be well served by even the entry level iMac. Computers are so much more powerful now than just a few years ago.
20" iMac with 2GB and AppleCare: $1500
(not killer, but will work for any normal hobbyist photography endeavor)
Mac Pro, most basic config, (single CPU, 2GB, AppleCare, 20" Monitor): $3150
Beginning of a high-end machine.
I believe you're set to over-buy. You can get a good machine and save $1500.