I'll try this later, but looks like a life saver. I also find myself sometimes screening through a post's comments to see which ones are new. Thanks for sharing this :)
no problem, let me know if there's anything I can improve
Is there an option to turn it on by default for every comment thread?
You could build this into something resembling the Reddit Enhancement Suite for Chrome...
you could use grease monkey to do that, or i could figure out how to make chrome/firefox extentions