We released Upgrade Pack 1 for customers that require a fully supported product from IBM. Also, some customers have policies prohibiting the use of open source projects like OpenNTF. Upgrade Pack 1 is covered by the standard IBM license.
However, the OpenNTF releases of extlib will continue to be more frequent than upgrade packs. Also, the OpenNTF releases include more content -- for example, the relational DB support. The extended content may eventually be rolled into a supported product, but we aren't making any commitments.
Does that help?
-- Dave Delay