Bitcoin’s hash-rate (the total computing power of the network, defined as number of SHA-256 hashes it can compute per second) has most likely exceeded the total computing power of all the world’s computers.
It’s an estimate that there are about 2 billion personal computers in the world. I would assume that the average hash-rate of these computers is about 10 MegaHash. 20 Billion MegaHash = 20,000,000,000 MegaHash = 20,000,000 GigaHash = 20,000 TerraHash = 20 PetaHash. The current hash-rate (at the time of writing this article) is a little over 20 PetaHash. So, most likely the Bitcoin network’s hash-rate has exceeded the total computation power of all the personal computers in this world combined!