Great - the softpedia download worked, thank you.
I don't know quite how the update failed, but it did - when I looked at Tunnelblick app in finder, it showed 104 bytes, and opening it via show contents, the folder structure was there, but almost no files.
I would second the call to abandon Sourceforge - there are other good reasons to do it apart from this latest debacle.
Cheers, Paul.