Heh. Back in Macworld Boston 1996, I bought one share of Apple stock at $16 and got a framed commemorative stock certificate. It went into a box when I moved later that year and I completely forgot about until I found it a couple of weeks ago. It's worth almost $1,000 now!
Unfortunately the state seized it as abandoned property (I moved a couple of times since and I never updated my address with the stock transfer agent) and I'm in the process of trying to reclaim the stock now. :(
Which is exactly the question I asked of the transfer agent, but it seems that if the TA can't get in contact with you over a certain period, they can consider the stock "abandoned".
Since I actually have the certificate (well, not anymore, I had to send in the original certificate to the state as proof of ownership), getting the stock back is a straightforward process. But until the state relinquishes its claim, the stock certificate literally isn't worth the paper it's printed on.
I have a friend who invested ~$10k in AAPL in 2003.
He's considering moving to NV or TX for a year,
to avoid the massive CA 10% long term capital gains tax..
we joke that Steve Jobs is partly responsible for CA's mass exodus.