If you haven't heard of Bitcoins before, I recommend you head over to http://bitcoin.org/ and watch their video. Bitcoin is a highly interesting decentralized and fully digital currency.
As of the writing of this article, the current value of 1 bitcoin is $23.28 USD. (see http://mtgoxlive.com/orders for one vision of current prices). This is huge increase over the last year. When I began collecting bitcoins and using them, the exchange rate was about half this value. There seems to be an ongoing discovery process where more and more individuals and businesses learn about and discover Bitcoins. This increase in interest, coupled with a more slowly growing supply is resulting in a currency that keeps increasing in value.
With may people discovering Bitcoins, one of the first challenges is the acquisition of Bitcoins. There are exchanges all over the place, but a lot of them use clearing houses such as Dwolla that add an additional layer of complexity. For Bitcoin to have value, and start being used for increasingly relevant and important transactions, people need coins. You could barter your way into the market, but it's easier to use a service.
Coinbase is a new service that will create a direct link to your bank account, and buy and sell Bitcoins. There are other services that operate this ways, but Bitcoin is partnered with US Bank, and seems to have a higher level of reputation and reliability. Coinbase has a real office in California. Additionally, Coinbase is operated more as a technical software startup than a Bank, focusing on the experience and the process.