Bummer, I hoped for this addition for a long time. Will there be an update to A6 or is this scheduled for the final commercial release then?
This is last alpha... After this, there will be beta. Beta will still not be final commercial release, but should have all base features. Those should be Shadow catcher, SSS, pFlow support, memory optimization, animated proxy, advanced layered shader, flickefree HDcache and possibly also interactive rendering. While i can not guarantee that all of them will make it into
first beta, i am quite confident shadow catcher will.
Actually, after this release (A6), the shadowcatcher is very high on the list of TODO features :) And since you probably have access do dailies, there is a chance you will be able to use it long before beta is out ;)