The latest notebook to be supported by the Coreboot open-source BIOS/firmware replacement is the HP Pavilion m6-1035dx, which is described as an "entertainment notebook" and features an AMD quad-core A10-4600M APU, Radeon HD 7660G graphics, a 15.6-inch display, and other modern functionality. The product number for the Pavilion m6-1035dx is B5S06UA.
Coreboot supporting this hardware wasn't too much of a challenge with basing the port off the AMD "Parmer" support and its ENE KB932 embedded controller doing little work. Shortcomings of this Coreboot port include the ACPI code from the EC not being hooked up yet so the battery level isn't exposed to the OS and the brightness control hotkey not working.
More details on this Coreboot HP Pavilion m6-1035dx port can be found via this Git commit. More information on supported systems by Coreboot are documented at Coreboot.org. For those looking for Coreboot preloaded onto systems, one of the only major sources of Coreboot-shipped hardware are Google Chromebook/Chromebox systems.