AFAIK nobody publishes details on sold magazines or RISC OS computers ... I never saw any and I rather not start that now. I must admit that the circulation has dropped quite a bit over the last years - mainly due to users moving to other platforms.
To SteveG and Lee:
I guess when a VirtualRPC is available for Linux then it should be no big feat to have it for Mac OS X since both are more-or-less Unix. But true, a real XScale Laptop with the uptime to go with would be nice indeed.