Cakewalk doesn't publish updates like MS. There are like 4 or 5 updates per year on software like SONAR and they get a lot of publicity. They are noted on the blog, in the forums, on the Cakewalk website splash screen and in the forums.
Additionally, if you go to the support page for a particular product, you are given a list (and links) to all the updates with the most recent at the top. On those pages there is a date (at the bottom - this could be improved) which states when it was last updated.