Lightroom by default comes up with Canon Tether plugin. Does it provide any SDK, using which we can build our own tether plugin that selectively takes files from an external source (server/folder)?
I could find none on Google search.
You may find the auto-import function useful. It watches a folder for new pictures and then copies them to your catalog automatically.
http://help.adobe.com/en_US/lightroom/using/WS1FAB59DE-8867-4052-BA02-5CF6C163CD29.html