It lets you search all gnuradio directories (of the metager hosted online server setup) for keywords, and will then show you any files that contain the keyword in their name OR contain the keyword in their contents. It will also show you a snippet of the file contents around the keyword you searched for.
If you've ever need to search for source, this is the tool for you.
I don't know how often that servers gnuradio install is updated, or any details on their situation at all.