Is the imagerunner 3220 a big improvement over the 3200? How does the 2620 compare to the 3220 and 3200?

The canon IRC3200 and 3220 are basically the same identical printer but the 3220 added MEAP capeability. The iRC3220 also has 1 GB of ram in the printer itself instead of 768 MB in the 3200 but I've not noticed any actual difference using the machine for printing, copying, or scanning from the additional ram, and I don't use any MEAP applications myself. The 2620 was just a "slowed down" version of the 3220 to sell at a cheaper price; I have no direct experience with the 2620 though. Toner, drums, fuser, transfer belt, etc. are the same.

There was a big improvement in the "standard" RIP - the Fiery imagepass C2 which comes standard on many iRC3220s is much much faster than the older Fiery imagepass C1 RIP that came on our iRC3200 for prints with raster content.