As long as Steve is around, the only upgradeable Mac is Mac Pro and as it's name and price says, it's meant for users who know how to deal with hardware (not that iMac owners don't).
This Forum is called "iMac, eMac, Mac mini - discuss Apple's desktop
consumer Macs" and I know I'm slightly peeved by it. I do not consider a machine costing 2000 (e.g. iMac 27" i7) to be a consumer machine. Anyone ready to shell out that much money either has at least a serious enthusiast/professional usage intent or waaay too much spare cash.
My previous preconceptions, based partially on what i myself have seen was verified by a school (MBA student) training assignment I did in january, targeting about 40 friends and former colleagues in the video/audio/graphics/photo industries. In this quick report I have intentionally omitted mentions of non-Mac hardware.
Now I know these findings should not be overly generalized or held as uniformly valid, but they illustrate an interesting point:
AUDIO (n=9)
The audio industry is clearly divided by the need for accessories and peripherals. If they are needed (and they wont fit a USB or FW port) then the weapon of choice is the Mac Pro (and in many cases still elder G5 PM's). The rest is evenly divided between MBP and iMac users.
VIDEO (n=7)
The Video industry has clearly been the Mac Pro's domain. Very few performance, storage and expandability -hungry professionals have found another valid alternative. What I heard, this might be changing, as many see the price difference between the iMac 27" to be too big an incentive compared with a MP and a 30" ACD (or 2X23"). Naturally as one agency's production manager pointed out, they are waiting to see what the next MP generation brings, but they are prepared to phase out one generation of MP's (1.1) with and replace them with iMac's in all cases when expandability is not an absolute necessity.
GRAPHICS (n=21)
The graphics/DTP industry has since the advent of the 24" iMac totally deserted all other alternatives. Based on my poll the iMac totally rules this field (> 90% in machines less than 3 years old), the exception being those who need mobility, who have gone the MBP 17" way.
PHOTO (n=3)
The sadder note came from the three photographers i questioned. They all hail the new iMac display to be a marked improvement, but state that they can't function without a display at least the quality of the 23" ACD (which they say the iMac's is not... Two of them used Mac Pro's coupled to dual FullHD displays (Apple's and Eizo's), one used a latest generation Mini with coupled with a 30" ACD (This was a surprise).
Based on some (somwehat unreliable) quantitative questions it seems that numerically the iMac now covers about half the professional Mac users in this quick poll, and whereas 27 said they expect to see even more iMac's in the near future. No one voiced the opposite expectation.
So I'd like to state that the iMac is very much an important workhorse in those professional fields, which have traditionally been Apple's stronghold.
The main reason stated for this by many of the interviewed parties is that the price differential between the Pro and the iMac has grown too big, and that the Mac Pro thus is the number one option only in those uses where expandability is paramount.
Naturally this places Apple in a precarious position... Tune up the iMac on the expense of the Pro or tune it down??? As the above mentioned production manager said: "Apple's gotta make the right moves. We spend more on software than hardware every year. We're constantly on the lookout for signals from Apple and will make the switch (to Windows PC's) the moment we do not see Apple moving into the right direction."
Slightly OT, but someone might be interested.
Pekka