Seti is a volunteernetwork for good cause. Don't think people will want to do this kind of work with there private machine. Also most pc's will not be strong enough to run the pano's we might want to have them render.
I was joking
And thinking of all the PCs on a private office network, rather than everyone out on the interwebs.
If you have a big computing task that can be broken down into small pieces, like SETI, Folding, etc, then having lots of 'normal' PCs available is very, very effective. And realistically, almost all computers these days are capable of helping out... as long as the chunks of data only take, say a couple of hours at most say to process, so they can do a few chunks per night...
When at work, i've wondered why we couldn't use the 100 or so PCs we had sitting idle for 16 hours of every working day, and all weekend... We had to wait for big FEA & CFD jobs to run (Finite Element Analysis, Computational Fluid Dynamics), which were run on an expensive unix workstation... but if we had the 'farm', then we could run jobs much, much quicker, or more complex/accurate jobs overnight that we couldn't on just one workstation. That would be much more cost effective, without the need for over-priced top-end hardware.
This is easy with open-source or free software, as there's no problem installing the farm client on all the office PCs you want, but with commercial products, you often pay per processor, so it very quickly becomes too expensive.
i don't know if processing gigapixel panos can be broken down into discreet chunks suitable for this kind of farming, but it's interesting to dream of