I recently set up a Linux server to play around with an host all my media. What is the best method to allow streaming of that content to an iPhone/iPod/iPad?
I've seen Plex used on Mac and Windows.
It streams well to iPad/iPhone and android devices.
There is a server called forked-daap (the original has become moribund here's the most active fork of the forked-daap) that can stream to iTunes on OSX
Update: Sadly forked-daap can't stream to built-in Music/Videos apps on iOS devices - the only daap servers the built-in apps will find are ones doing Apple's Home Sharing (which makes use of a user's Apple Id).
To try and make amends for the above misinformation let me list some of the 3rd party iOS apps that can stream from another server and which protocols they can use: