4b. sounds reasonable, although I can dream of projects where it might be 
a limitation. 4-byte source pointers might be preferable if there are no 
performance penalties or implementation issues.

Performance, incidentally, has been simply stellar for me on modern 
hardware. The Squeak VM is approximately 1/10th the size of commercial 
Java VMs, and seems more robust in almost every way. 68K Squeak has been 
usably pokey.

I'm still new to Smalltalk and to Squeak, but I can tell already that 
there will be no turning back for me. I simply cannot imagine returning 
to C, Java, and so on. Thanks for making this available. At last, there 
is a free, open, crossplatform programming environment that can actually 
be used.