Few months ago I had installed OP and did some customizations. The site never went live. I want to get back now and update to the newest release. As I see here http://openpublishapp.com/download there are specific version guidelines on update. So, what version am I running?

OpenPublish must advertise the current version on status page like Pressflow or OpenAtrium does, on admin/reports/status, by implementing a hook_requirements().