I've tagged and released Smack 4.2.1 to Maven Central. We decided to omit the smack-omemo* in this release packages as the API is not yet stable. Paul is currently working on encrypted Jingle Transports as part of his GSOC project which also involves OMEMO, and we probably will make some API changes to the existing OMEMO API because of that. As always daily snapshot builds are available from igniterealtime.org/repo.