Line 41 assigns the params object to $params.
Line 51 accesses $this->params which was never assigned.
It doesn't seem to matter much if the variable is local or a class property (although having access to it in the template might be useful) but it should be one or the other.
I'd love to post a follow up to that thread but joomlacode.org is STILL broken. When are you guys going to shut that thing down and get a proper bug tracker?
Looks like my follow up was posted after all. However, I was immediately logged out upon posting. Half broken is still broken.