They're being moved to the newly created areas that pertain to socket type. You may want to check in those.
Due to the ever-changing popularity/quality of certain motherboard manufacturers, not to mention chipsets, we have decided to reorganize the motherboards section according to socket type. This means that all manufactuers and chipsets will be lumped together according to that criteria. It provides better long-term forum management.
Depending on what you're looking for, check the various new forum sections categorized by socket. You'll find what you're looking for.