Interestingly, I have two different version control systems for doing these two different species of commit. The published kind, I do in my regular team version control system, complete with commit comments that explain the meaning of the complete thought that is being committed. The other kind (bookmarking my state before messing around with things I may want to cleanly revert) I do using the version control that is built into IntelliJ IDEA. It is completely orthogonal to the one used by my team.

Other IDEs should offer this feature... it turns out to be quite useful in practice.