When trying to associate MeshLab application to all the .ply files with the Always open with or Change All... buttons I get the following error
An unexpected error occurred (error code -10813).The operation could not be completed.
The problem is that MeshLab is missing the key CFBundleIdentifier in its Info.plist.
To solve the problem edit its plist file
> open /Applications/meshlab.app/Contents/Info.plist
and add the key CFBundleIdentifier with value com.vcg.MeshLab.
Then touch the application tell OS X about the change
> touch /Applications/meshlab.app
And retry associating the file type.