I did some work in 2.7 on explicit metaclasses in Squeak. I added a
#primitiveChangeClass to the VM to modify the class of an object and also
Object>>#class:

I have not had time to do more work on the explicit metaclass stuff due to
work and have been reluctant to have a go at compiling the 2.8/2.9 VM as it
sounds very volatile.

Have a look at http://sites.netscape.net/pinkles/neosqueak

It is still very immature and I havent't apudated the web site in months but
the VM changes seem to be ok. If you are into compiling your own VM and just
want the change set let me know (the .cs is much smaller than downloading th
2.7VM).

I too would like to see the primitve added to the base image. It makes the
SUGAR guys object\instance protocol much simpler.

Groete,

Brent