Absolutely! This is practically guaranteed. I tend to feel like 2-3 years is a good span for an "upgrade" to a "next step" experience; you can drag it out to 4 years, but then you're starting to get into the next cycle.
With all of our family Macs, we had gaps of at least 6 years between new machines (not counting a beige G3 bought reconditioned toward the end of 2000). That's a bloody long time, and you miss a lot of "progress" by waiting so long. Therefore, each new machine felt like it came from another planet and left the older model(s) in the dust. My most recent upgrade was an early-2008 iMac, preceded by a 2002 G4 "Quicksilver." I won't be waiting so long again. (I'll pull the trigger on the next iMac refresh, probably, or a Mac Pro, once the software I use can take efficient advantage of so many cores. The fingers be a-tappin'...)
I have a feeling that the iPad will undergo some rapid improvements, as long as they can develop faster processors while retaining the same energy efficiency. We just have to wait for the initial surge to relax and let Apple decide where they want to go with it.