Can I use a butterfly-labs miner to mine any crypto-currency?
Look at http://dustcoin.com/mining. The currencies designated as having SHA-256 algorithms (e.g., Bitcoins, PPCoins, Namecoins, and Devcoins) stand a good chance of being mined with BFL-like ASIC mining hardware. Remember, some currencies support merged mining - mine once and get paid in multiple currencies. Either your centralized pool supports merged mining or you have to do it on your own.
The Butterfly Labs miners definitely work for Bitcoin, I have one, it works as advertised (better in my case) and mines successfully.