Indeed, it is not.
According to this post
in another thread, as of two days ago, the WiiWare version was still in development.
After that, Telltale still has to submit the finished version to Nintendo, who then has to approve it and set a release date.
In other words, it will be a while before it is finally safe to say that the WiiWare Puzzle Agent is cancelled.
There's even a good chance it will never be safe!