Type safe events have been one of the most elegant and innovative features in CDI for a long time. For some odd reason however they seem to continue to be fairly under-appreciated and not written about that often. It's very good to see CDI specification co-lead Antoine Sabot-Durand recognizing this and aiming to do something about it. In his most recent blog post, Antoine wrote up an excellent refresher on CDI. He covers the basics of events, some of the more advanced features as well as some best practices. The blog post actually covers some of the more fine grained changes in CDI 1.1 and CDI 1.2. Antoine also briefly talks about some of the possible enhancements to events in CDI 2.
It's definitely well worth a read if you are already a CDI fan or just beginning to explore it. Do pass the link on if you know anyone that may benefit from it. Note that the upcoming GlassFish 4.1 release will support CDI 1.2.