In case you didn't know Kobo has a really good blog at
http://blog.kobobooks.com/ This is especially good as they even included images showing you what some of the changes look like and samples of the new fonts.
They also have a Facebook page at
http://www.facebook.com/kobo and a Twitter account at
http://www.twitter.com/kobo so there are lots of ways of keeping up-to-date (and of course firmware releases are always announced here too!)