It would be great if integration with GitHub commit status API would be available. In this way CSS lint could be automatically call on pull requests to check the code and provide feedback.
I'm not sure what you're asking for. CSS lint already runs on Travis CI, so all pull requests will display build information from that. Is that what you're looking for?
Not pull requests against CSS lint itself, but for my projects I have on GitHub, it would be great if it would be possible to run CSS lint as a hook on the pull request. Maybe integrated into Travis CI. But maybe also independently.
you could run csslint in your travis build within your buildscript... shouldn't be a problem?
CSS Lint can be run independently on the command line, but it's up to you to integrate into your build system appropriately (which can be done pretty easily, check out: https://github.com/stubbornella/csslint/wiki/Build-System-Integration