"PowerPlay is supported with that chip, but HP could have just not included the power play option on that model of laptop."
Is I understand this, PowerPlay should actually be possible on all RS780 Chips, but has to be enabled in the BIOS? What is exactly this "power play option"? I hope also for a new BIOS, but actually I don't think the vendors will roll out a new BIOS with support for that. I have hopes in the coreboot project, to which AMD is contributing also at the moment (Thanks for that, too, AMD!).
www.coreboot.org

Still not sure, if this could be fixed with a new BIOS theoretically.