I recently came across this article about github pages.

If you make a repo with name same as your username then the content of the repo is hosted as subdomain http://YOURUSERNAME.github.com

Read here: http://help.github.com/pages/

So now you can host your blog at Github sub-domain for free and update via Git. Cool! B-) But as Github will not really provide you a server running php, mysql, etc so the limitation is it has to be static, but no worries, Jekyll-Bootstrap comes to rescue here. It’s a static site generator which would generate the html for you and then you can push it to you blog via git. Bingo!

EDIT

They changed the domain for your webpages from http://YOURUSERNAME.github.com to http://YOURUSERNAME.github.io so you will have to create the repository with the same name.