One of the major flaws in these kind of stories is liquidity (or lack thereof) on the exchanges. Try selling anything more than a few 'coins' at once at these kind of prices and see the price fall. Mt Gox rate was halved in price briefly last week by the sale of ONE HUNDRED bitcoin. This $1000 thing is a false price, elevated as much by hoarding and lack of large scale trades as anything.
Lots of luck trying to cash in $4M worth, you'd bring the price down to single figures all by yourself before you were anywhere near.
And that's apart from the difficulties in getting out any real cash you've managed to trade BTC for. MT Gox are only allowing withdrawals in dribs and drabs, and they'll probably be regulated out of existence altogether before long. And in the UK, there's really no practical way to get out large amounts at all.
GO Bitcoin. To the Moon etc etc