Append get parameter on static paths to force content expiration in build process

Question

I've noticed a lot of sites, including stack overflow append ?v=36556 to their static file path to force the browser to re fetch the new version. On the stack overflow podcast it was mentioned they do this as part of the build process. I'm just wondering if there is any existing msbuild tasks or utilities for doing this? Or should I just roll my own?

Thanks