output like "port list all" over the web?

[Richard L. Hamilton]

The more I think about it, there's probably not as much that MacPorts and MacUpdater can do for each other as with brew...because brew also provides procedures ("casks") for installing commercial software and/or checking for the latest version.  MacPorts doesn't do that, it only installs open source (if with some few cases where binary redistribution is precluded because of incompatible licenses).  Portfiles are kind of analogous to brew casks, but the format and  information in them is different; and MacPorts isn't really meant to be updated by anything else (give or take an occasional attempt at a GUI).

It's perhaps a bummer that there's no identifier that I can find that indicates that a particular .app bundle was generated by MacPorts; that would assure deconflicting with other updaters.  But usually those app bundles are in /Applications/MacPorts or below, and leaving that alone should hopefully be sufficient; and both MacUpdater and MacUpdate Desktop can be told to ignore directories (although the latter may not always ignore them as one might expect, although maybe it just doesn't ignore subdirectories too).