to elaborate, with the right set of software hacks, a PCMCIA video card for the Powerbook, and by destroying the iMac completely, you may be able to get this to work, so... no.
I can think of a couple of software approaches: VNC and X11. But I don't think either of them will do the kinds of things you're thinking of. (There's Apple Remote Access and Timbuktoo too, right?)
Besides, the Powerbook's screen resolution is much greater than the CRT iMac.