When bitcoins first started they were mined with your CPU power, people soon found out they could solve the SHA256 equation much faster with GPU’s. This led to an increase in GPU sales and video card manufacturers cried happy tears. FPGA mining was a short pitstop for bitcoin miners, and was quickly replaced when the first ASIC bitcoin miner was released. ASIC is specially designed peice of hardware made for solving the SHA256 hash required to mine bitcoins.
If you’re looking to get started bitcoin mining you can start off small, and possibly be victim of having the difficulty rise to far, and render your hardware useless. There is the option of Pre-ordering hardware, and possibly getting the next big miner before the masses, this might be a reasonable investment if you’re already mining bitcoins and can afford to take the chance on late hardware. There are several options available as of now where no-wait is involved but these will change as new ASIC products are available.
Here’s a video explaining the basics of bitcoin mining.
As im writing this, There are USB Block Erupters and ASICMiner Blades in-stock in several locations such as MinerSource.net