Ogg doesn't play over Airtunes

iTunes doesn't stream ogg over to the Airport Express. There is a bit of software which can do it though, for $25:

http://rogueamoeba.com/airfoil/mac/ 

Once again, MP3 seems to be the best choice - with hindsight.

Play ogg files in iTunes

Downloaded a Quicktime plugin version 0.1.8 from Xiph.org, as suggested. Dropped into /Library/Components and it plays Ogg.