The Bitcoin IRA - Businessweek

I recommend reading A Short History of Financial Euphoria before investing your retirement (or other) savings in Bitcoin

"The Bitcoin Investment Trust isn’t the only way to bet your retirement on the value of Bitcoin. People have already found other ways to do it. Tym Blanchard, who works at a chemical company in Charlottesville, Va., says he set up a Roth IRA to invest in Bitcoin directly, purchasing the currency through Coinbase. While he expressed some wariness that traditional investments tend to move in line with one another, he was also looking for tax benefits. “If the currency is still thriving by the the time I’m allowed to make distributions, the tax savings will be enormous,” he wrote in an e-mail. “I enjoy taking risks.”
What SecondMarket offers is a far easier way to do this. Buying Bitcoin is complicated and storing it is fraught with danger from hackers. Basically, this offers investors who want to ride the wave but don’t really understand the nuts and bolts of the currency a way to do so."

The Bitcoin IRA - Businessweek