If all goes well with Intel's 22 nm process, Haswell is scheduled for Q2 2013. 2012 (Q2 onwards) will be led by Ivy Bridge. But then here's a "shocker": Haswell's desktop version will use a brand new socket, LGA1150, and will be incompatible with LGA1155. This is because of drastic changes in the pin map of the package. Sandy Bridge and Ivy Bridge share the LGA1155 socket, and will hence, have kept the socket alive for over 2 years. A major change with the component arrangement in the platform that is affecting Haswell's pin map is that Haswell will have a higher bandwidth chipset bus, rearranged PCIe pins (with FDI pins), rearranged power pins, and miscellaneous pins. It does away with a separate power domain for the integrated graphics controller.
Haswell will bring several new features to the table, including next-generation RapidStart quick boot capabilities that reduce cold-boot times to 2 seconds. The processor's IPC will be increased over Ivy Bridge. The mobile version will include features that will further increase battery life of mainstream notebooks. Haswell will feature improved media HD to HD transcoding capabilities. It will bring technologies such as NFC (near-field communication), and Thunderbolt (10 Gbps interconnect) to the masses.
Moving on to the platform itself, it is named "Shark Bay", and will be available in 2-chip quad-core and 1-chip dual-core variants. The quad-core chips and some dual-core chips will use the usual socketed motherboards with a single-chip chipset (PCH) which is smaller than today's PCH chips, while the some dual-core chips will completely integrate the PCH into the processor's package, eliminating an external chipset. The dual-core chips will be available in BGA packages.