A cool thing you could do with this is adding a javascript function in the file that automatically submits a story when this button is included. That would really elevate it from a link with some styling to something that's really useful.
BTW, I don't like the word 'Follow'. Follow might've meant something else in the long-forgotten past, but right now, it means 'subscribing to someone's rants on a social network', which is _not_ what you mean at all. I think 'Discuss on HN' or 'Discussion' or something like that would be a much better title.
It's broken in IE7, IE9 (not IE8) and Firefox 12. The logo's button element on the left doesn't align with the one on the right.<p>Is there a specific reason you chose to add a button element in your links? Why not style the a tags and display them inline-block?
I like this idea, however at first i thought it was allowing me to get notified of updates on a particular HN thread. I guess what i'm trying to say is maybe there is a better word than follow.<p>In general, i really like it though! Well done.
BUG: It's not properly aligned in Safari 5.2 (beta), OS X Lion 10.7.3:<p><a href="http://d.pr/i/ZDZM" rel="nofollow">http://d.pr/i/ZDZM</a><p><a href="http://d.pr/i/Gj25" rel="nofollow">http://d.pr/i/Gj25</a><p>Is perfect on Chrome though.
Something you may consider for your CSS: vendor prefixes are no longer required for border-radius declarations.<p>Mostly true for box-shadow as well, except for the Android browser I think.
updated the git.<p>- renamed from "Follow Discussion" to "View Discussion"
- improved code, thx to @TazeTSchnitzel
- tested with Chrome 19.0.1084.52, Safari 5.1.3, Firefox 9.0.1<p>just discovered that <a href="http://nreduce.com/" rel="nofollow">http://nreduce.com/</a> is using the button