I was wondering if it possible to upgrade FC2 to FC3 by just mounting the ISO's and not burning them....

You can do a ftp/nfs install but that still requires booting off a media cd.
You *might* be able to do it through yum.

Download and install fedora release, and the yum, and install the gpg key for fedora.
Then run yum update and see if it says it can do it.

I don't know if the python on FC2 will work with the new yum though.

Hi i did a upgrade to fedora c 3 through yum yesterday worked like a charm only took about three hours too (wich is quick for me lol) I could not belive how easy it was just downloaded fedora realese and yum, typed yum upgrade and it went through n tested everything it came back with two dependency errors one concerning xine the other gdesklets. I removed both packages and restarted n it went as smooth as a babys bum!
Im now using fedora three with no problems at all. Im sure there will be a fix for gdesklets soon for fc3.

Edit: just built gdesklets from source n all is good GoodWeather running fine with fc3

Mount the iso and read the instructions. If there isn't a live install option, there may be an install from hard drive option where you supply the location of the iso files, rather then mounting them. You may need to produce a special boot floppy in order to do it.