All happened last September. They are planning it again, and hoping for many more boats in order to grow it into a much larger event.
It's not a race at all and you are right in that it's really a cruise.
There were a couple of Hoorays, but generally a good bunch of people.
There was no charging involved so no MCA/Thames regulations breached.
There is another thread on this from last year with quite a bit of knocking going on between forum members and the organisers which at times got quite comical.