Ghost is a great blogging platform but the lack of LDAP support makes it not too ideal for Freeside. The only blogging platform that support ldap with the use of plugins is wordpress (yuck).
One option would be to use Jekyll since we already use git extensively we already have the infastructute to automate deploying updates to Jekyll as well. Another option would be to write our platform. Hell we could even use the discourse API for our blog.
If anyone knows any other blog platforms which we could use, let us know