Let's talk hypotheticals.
A client walks into your office, and says, "I want to hire you. And I will pay you 1 million Monopoly dollars for your services." You would politely decline the offer, right?
Now, let's tweak that scenario. A prospective client saunters in and offers to pay you 1 million in Bitcoin to represent him. This might actually work.
In the government's eyes, Bitcoin is no more "real" than Monopoly money, but the financial markets think that it has value. Wednesday, CNN Money reported that one Bitcoin was worth approximately $49.
But what exactly is it? PC Advisor explains:
Bitcoin is an online, decentralised, crypto-currency, that is monitored and administered by the massive peer-to-peer network that uses it. The currency has online exchanges that trade in the commodity, one of which - Bitcoin Central - recently partnered with a French bank to become a registered Payment Services Provider (PSP) under EU law, meaning it can now offer debit cards, account insurance, and many other normal banking facilities to Bitcoin customers.
While it may be illegal to make and circulate your own physical currency in the U.S., Bitcoin falls into a legal grey area, ArsTechnica reports. Some politicians have denounced Bitcoin after learning that it was used in drug transactions, but it's not clearly illegal. (And, let's face it, cash is used in criminal transactions all the time. Hate the criminal, not the currency.)
Accepting Bitcoin for your services is essentially a barter exchange, which appears to be allowed under the professional responsibility rules. (If you're unsure whether your jurisdiction allows you to barter your services, you can always submit an ethics inquiry.) The main limitation on fees is that a fee must be "reasonable." Granted, it's harder to determine what is "reasonable" in the context of cyber-currency, but you could use U.S. dollar exchange rate as a guide.
The question of whether you should accept Bitcoin really depends on you as a person. If you're actively engaged in the online community, Bitcoin may be a better bet than the dollar. If you live in the brick-and-mortar world, you may have a hard time spending it.