No, that feature isn't directly available on the GitHub web interface (as opposed to the "Revert" button recently added for GitHub for Mac/Windows)
Actually, it is for pull requests only, since June 24th, 2014:
Introducing the Revert Button
you can easily revert a pull request on GitHub by clicking Revert:

You'll be prompted to create a new pull request with the reverted changes:

git revertgit revert is a bit more complex to manage through the web as it can accept a range of commitcommits.
It shouldn't be an issue in termterms of collaboration though: a revert adds a new commit, it doesn't change the history of existing commitcommits.