In the first Bitcoin theft of its size, a user has lost 25,000 BTC — or nearly $487,749 at today’s market rates — to an unknown thief.

While the Bitcoin community has always been quick to point out that it’s harder to forge a Bitcoin than to forge a dollar, it’s quite easy to take someone else’s Bitcoins: all you have to do is gain access to their computer’s hard drive. Once you’re in, stealing Bitcoins is easier than taking a wallet in the real world, and there’s no recourse for getting them back.

That said, it is possible to verify the movement of funds to ensure complainants are telling the truth due to Bitcoin’s public nature — services such as BlockExplorer allow users to see every transaction that has ever occurred through the network. The receiving account in this case, for instance, can be seen here.

As a decentralized network with no authority and no identities attached to the addresses used to send and receive Bitcoins, once Bitcoins are stolen they’re as good as gone.

While at the time of this writing the BTC is trading at $19.51, I wouldn’t be surprised to see their value drop over the course of the day as this news spreads.