Looks pretty twitter bootstrap like, if you ask me. I feel that a lot of designs are ending up like this due to bootstrap influence, which, might be influenced by dropbox for all I know.
The overall homepage though I think looks nothing like Bootstrap's docs, if that's what you're implying. Also, Bootstrap, and GitHub, was not influenced by Dropbox. We just iterated on that stuff internally in a pull request and shipped when we were happy with it.
Either way, I don't think it matters. It looks good and clean.
Not trying to be critical by the way. I'm a huge fan of every company/framework/person etc mentioned here. I'm just really interested in the form, function and messaging of homepages.