Playlists are soon to be available in the both the Web and iOS clients per the most recent blog post: https://blog.plex.tv/2014/03/13/chromecast-free-everyone-great-new-features-ios/
This is very exciting because from what I understand, lack playlists was the major hold up of a lot of interesting uses; including something similar to PseudoTV: http://forum.xbmc.org/showthread.php?tid=90738
As the details of the playlist feature start to emerge, I really hope that they're third-party developer friendly enough to manage something like PseudoTV, as I think it would be a VERY welcome addition to Plex.
