@Neil
I absolutely agree that people shouldn't complain about Microsoft releasing properly labelled public betas. Every major application vendor has a beta programme, because internal testing doesn't necessarily use the product in the way that real users in the real world manage to do.
But I thought the big complaint with the Vista SP1 was not its mere existence, but that
(a) it's such a pain to satisfy
(b) (I suppose at least warns you that) installing it is going to leave you with a system that won't take the final beta when that's available
(c) finished with an RTM that wasn't made available to TechNet/MSDN until a whole load of people kicked up a big fuss.
(d) took so long in coming, when pretty major problems (like the file copy performance) have been trailed as ready to fix in it for months on end, and users have just had to live with until then.
Having said all that, my box remains un-SP1ed until the rumours about the RTM triggering iTunes problems go away.