Ok, I added an optional PiPSqueak feature to WindowSnapper. Its job is to "squeak" the "main" (first) window into an empty PiP slot (this is what you're looking for, olipcs and Dragonshadow).

PiPSqueak is not 100% compatible with Zanthor's current multi.iss/wow.iss configuration, there would be some minor conflicts that can be fixed relatively easily (join the IRC channel for help if needed, or wait for Zanthor to update them eventually ). When not using PiPSqueak there will not be a conflict with the new version, though.

It's explained on the WindowSnapper wiki page, but in a nutshell, you would download and install the latest WindowSnapper (2008-11-18), make sure you have the latest build of Inner Space (restart it to automatically patch), then do the following in the Uplink (main program):
1. Open the console (right click IS icon, select Console -- also note that this console is just a window that opens in the Uplink window, there is a main console available in each session)
2. run pipsqueak to start the script
3. Set up the regions you want using the pipsqueak command added by the script, e.g. pipsqueak -slot 1 0,0,1680,840 -slot 2 0,840,420,210 -slot 3 420,840,420,210 -slot 4 840,840,420,210 -slot 5 1260,840,420,210
Note: that's X,Y,Width,Height, so you only need to change the X,Y for the PiP windows unless you would prefer different sizes That's 1 1680x840 main window at the top of the screen, with 4 PiP windows along the bottom. You can do each slot separately with the pipsqueak command if you want as well, instead of all on the same line.
4. Launch game sessions

Alternatively, autolayout can now be used in the Uplink in order to use PiPSqueak (it can still be used the same as before on a per-session basis), so:
1. Open the console (right click IS icon, select Console -- also note that this console is just a window that opens in the Uplink window, there is a main console available in each session)
2. run autolayout to start the script (or run autolayout 3 if you will be launching 3 sessions instead of 5 for example, and this will make room for 2 PiP windows instead of 4 PiP windows -- the autolayout script takes the same parameters documented for the autolayout command on the WindowSnapper page, e.g. run autolayout 3 outer left)
3. Launch game sessions

So there you go olipcs, should be what the doctor ordered