http://www.walletrecoveryservices.com/Possible!
If, however, you have a vague idea of your passphrase, but can't quite remember it... Then we can help you.
For instance
If you thought your passphrase was probably 'TheIceMan123', but weren't sure about what capitalization or suffix number you used, then we can help.
If you were sure that you wrote down the passphrase 'Hdd%&7d77ddH#3@4' when you chose it, but now it will not unlock the wallet when you type it in, then we can help.
If you were pretty sure that your passphrase contained words from a sentence from 'The Return of the King', but you've forgotten which page, then we can help.
If you reckon that your passphrase is some permutation (with some spaces or maybe capitals) of 6 of the words in the list { 'fred', 'hello', 'from', 'Butter', 'elephant', 'if', 'unlikely', 'green', 'grep', 'gorilla', 'antelopes' }, then we can help.
Decryption Service
We have created a highly optimized multi-threaded C++ program to perform the brute-force decryption. This service is designed right from the start to be a scalable solution - it runs on a cluster of high performance Linux boxes, hosted on the Amazon EC2 cloud. This enables us to scale up to nearly any number of computing cores. We have tested this with up to 100 8-core computers, but more can be brought online if required. The algorithms used to generate the passphrase permutations are proprietary, but are designed to be flexible in order to handle unusual requirements. The encryption used by the Bitcoin wallets is much harder to break than most encryption schemes. A technique known as 'key hardening' is utilised, so that it takes most home computers a full 0.1 seconds to check just one passphrase for correctness. This is why an optimised, distributed, specialized program is required to attempt large numbers of brute force decryption attempts. Update: 21 July 2013: We have improved the service to include decryption of blockchain.info wallets too! If you have forgotten your mobile wallet (blockchain) password, but have (or can get) a copy of your wallet.aes.json file, then we may be able to help. Contact us.