https://blog.documentfoundation.org/ triggers a security warning in Firefox, which refuses to show the site because the SSL certificate is for *.wordpress.com, not for blog.documentfoundation.org
There is no such HTTPS URL for the blog. ;-) If you need HTTPS, it is https://documentfoundation.wordpress.com (hosted WordPress)
This HTTPS URL is returned for at least some web searches by at least one search enging (namely duckduckgo.com), which probably means there is at least one link to it somewhere; I did not manage to find where. I noticed the issue because people that were web-searching (with duckduckgo) for things related to me found https://blog.documentfoundation.org/2012/06/26/developer-interview-lionel-elie-mamane-libreoffice-base-maintainer-and-volunteer/ , and they email me asking why my interview throws security warnings in their browser.
Oh, I am sorry to hear that - in fact, the SSL never worked, as this is (still) a hosted blog. Sadly, there's no short-term solution. We want to pack the blog to our own server, but right now have a higher prio for other tasks :(