Googlebot the Nomad

So we’ve got the Deskbar and the Google Toolbar and they’re great. I’m assuming one of you geniuses can probably fill me in on a larger question, though: Can Google ever make a desktop search engine, not merely a web client, with indexing of my local content like email or files? I am just curious, because it seems as if any effort to do so would reveal the PageRank algorithm, either through someone hacking the engine executable itself or by analyzing the data index that the bot would create.
Does this mean that poor Googlebot is cursed to wander the net all his days, never finding a home on a single machine? Never resting? Poor weary Googlebot.