i've done a lotta stuff with PHP socket connections and flash. as far as i know, it would take a lot to replicate flash comm's audio and video streaming using sockets. u could not do this in anyway using the flash xml socket object in flash and a socket server, as the xml socket only accepts text strings. u'd have to build some type of framework which replicates FCS in its communication with flash.
however, u can do a lot with strings, liked developing chats, drawing boards, games.