It was something that first came up over a decade ago as the comparisons between the human brain and the hard drive became popular, namely the difference between memory and storage.
Memory is just like storage, except that it's not binary, it degrades over time, and this is, in general, merciful. Storage, by contrast, is forever (theory only, viz. Nicholson Baker). If we confuse one for the other we lose a certain sensuous aspect of living. The part that has something to do with forgetting.
This has new implications, however, now that we all have access to google -- and then also vice versa. Because it caches pages, it doesn't matter if you rip them down -- or even if the high court orders them ripped down. It's cache. It's not a snapshot of all the information out there, it's an archive of all the information that ever was, and that's not memory at all. Maybe it's even the opposite of memory.
All of this is danced on and around in today's New York Times, which brings up an interesting new idea about the whole thing: that there's something sort of, you know, unpatriotic, about a public permanent record: "It is becoming more difficult to keep one's past hidden, or even to reinvent oneself in the American tradition."
It gets more interesting when they bring in David Brin, who wrote "The Transparent Society." The sense of privacy being violated here is related to -- says Brin -- "the anonymity of urban life [which] will be seen as a temporary and rather weird thing."
So if you solve for P and Q, this anonymity of urban life is somehow inseparable from the American dream of re-invention. This may not be news, except that somehow, it is today.