I don't think I agree here (politely), there is a fix which works for some people by mapping the Memory in Open Firmware, some got lucky, not me though.
Here is the link to that fix.
I could try to what you say but I am in Indonesia now and I do not have access to either a heat gun nor an oven.
I know this article, but one thing is against logic there: if it would be firmware issue, all PBs with certain firmware would be affected and it should happen right after update to this particular version.
Apple would rather release firmware update instead of this.
Second, these commands are only faking OF to "think", that there is RAM installed. If OS will start to use this "ghost" memory, it will crash, freeze or KP.
BTW, in similar way you can disable faulty soldered-in memory in iBooks and 12" PBs.
I've read some about this issue long ago and found few reports of users who fixed it with hot air. Even on MR was an old thread with such report AFAIR.