Just found on MacOS X Hints: ClipboardSharing is a Mac OS X application that allows you to share clipboard contents on the network.

Downloaded and installed. It seems to work well. It might be the ultimate solution for all my dual Mac usage problems (I always have something I need on the other Mac).

I'm afraid that this is the kind of feature that most likely Apple will incorporate some future version of MacOS X. Meanwhile congratulations to Erik Lagercrantz for the great idea and implementation.