I'm not quite sure where the news is here. IBM has been licensing the architecture and cores for years (2007 is mentioned[1]).
All I see in the actual announcement[2] is marketing hype (not news) about software that already exists ("open firmware" == U-Boot, "open software" == linux) and hardware that has been licensable for years.
Reading the press release, the firmware mentioned is neither das u boot (a bootloader) nor "open firmware" [1] a boot standard used by IBM's Power systems. It is the actual chip firmware, and this is the first I've ever heard of a silicon vendor doing this! I'm excited to see what the open source community will be able to do with it.
ARM is an "open" architecture—it's fairly easy to roll your own if you have an FPGA and patience to read through arch specifications for a couple months. I would be highly surprised if you could get equivalent documentation for POWER without a significant bit of cash. Not that I blame them, even open standards can cost a couple hundred.
I don't think this would change anything, though, there's not enough gain to justify an architecture switch for either hardware or software people. And that's a damn shame. I cut my teeth on PowerPC and I couldn't imagine a better way, it's a beautiful architecture. Altivec STILL makes intel's vector processing look like a toy.
All I see in the actual announcement[2] is marketing hype (not news) about software that already exists ("open firmware" == U-Boot, "open software" == linux) and hardware that has been licensable for years.
[1] http://en.wikipedia.or/wiki/Power_Architecture#Licensing
[2] http://www-03.ibm.com/press/us/en/pressrelease/41684.wss