If you haven't seen, there is a new version of the Adobe FDK, 2.5,
released yesterday. (
http://www.adobe.com/devnet/opentype/afdko/). Of
note is the new feature file syntax, which is detailed in
NewFeatureSyntaxIn2.5.txt, in the Technical Documentation folder of
the install. I don't belive that many shipping apps support any/most
of the newly available lookup types, but one can test things in Tal's
FeatureProof (
http://code.typesupply.com/wiki/FeatureProof), they'll
work there.