It's an unfortunate characteristic of windows this apparent lack of initiative regarding SCM. Everything that mattered (at least to my knowledge) was ported from Linux. However both CVS and SVN are widely used now; despite torvalds criticism I find SVN almost everywhere I look.
Baazar would indeed be a great addition to windows. It's philosophy of providing compatibility with other SCMs may still prove to be its biggest asset in both the Linux and Windows world.