This method of spreading isn't new...
This method of spreading isn't new - quite a few recent (and many not so recent) viruses use this method, along with the usual other methods, to spread.
And, as usual, it's all been nicely configured by Microsoft by default to ensure that it's easier for viruses to spread...
Auto-run for devices is enabled by default, hiding file extensions for known types is enabled by default, hiding hidden files is enabled by default (which does make sense, them being marked as "hidden" and all). All we need is a "feature" or technology in MS's browser to automatically install and run software from any old website that has full access to your local system and we'll be well away. Oh, wait - that's in place already.
All we need now is a "search" feature that can't be bothered to actually search your hard disk properly for unwanted files and... oh wait, that's also in place already. Just install the new "desktop search" which, erm, apart from being very, very slow also manages to break the normal "search assistant" search when installed. The really useful thing about this new search is that's it's been commingled with MS Office 2007 such that you can't use the search facilities of Office 2007 without installing it.