Good to see them supporting Kramdown as the default Markdown converter. When building up my personal website using Jekyll, I very quickly switched to Kramdown from the default Redcarpet—it had a lot better handling of typographic characters like smart quotes and dashes, and played much nicer with Mathjax.

Collections also look like they will really help with creating websites that deviate from the exact "blog" format that Jekyll is optimized for.

Good work from the team.