As a courtesy to early adopters I am posting a link to a custom binary of MacVim that I currently use on Snow Leopard (+cscope, +perl, +python, +ruby, +tcl, 32 bit Intel, 10.6 only). When I get time I will make a proper snapshot and post it via the usual channels and remove this binary [edit: it has been removed now]. Note that I cannot provide any support for this binary. If you do run into problems I would appreciate if you report it on the vim_mac mailing list (not in the comments here).
You can always build your own binary but do note that the icon generation currently is broken. This can be worked around by commenting out lines 52-57 and 242 in the src/MacVim/icons/docerator.py script. All build issues have been fixed now and the build procedure has been simplified, so go ahead and build your own 64 bit binary — it has never been easier.
To conclude this story: I have now uploaded a new snapshot that will run as 64 bit on Snow Leopard. Enjoy!