For any readers uncertain of exactly how the heartbleed vulberability in openssl might be exploitable, Sean Cassidy over at existential type has a good explanation.
And if you find that difficult to follow, Randall Munroe over at xkcd covers it quite nicely.
My thanks, and appreciation as always, to a great artist.
Of course, Randall foresaw this problem back in 2008 when he published his take on the debian openssl fiasco.