Hi. I'm working on a version to include quoted phrases. The reason that quoted phrases are not available in PhpDig 1.6.2 is that only keywords are stored in the database table.
Currently PhpDig loops through the keywords and decides what results to display. Because keywords are used, you can search "exact words" meaning find me results containing these two words.
Not sure if that made sense, but anyway I recently heard about
ADOdb. It sounds pretty cool and allows caching of recordsets for a specified time.