I heard that some people have been arrested and charged with "transmitting money without a license" for selling Bitcoins.
Does this mean it is illegal for me to sell my Bitcoins?
I was arrested for selling my Bitcoins using localbitcoins.com
I paid all of my capital gains taxes on all of my trading - that was not the issue. The legal issue boiled down to one question: was I operating a business or not. They claimed it was a business, I claimed it was not. After being forced to "donate" about $40,000 in cash and $40,000 in Bitcoin to their Federal Asset Forfeiture slush fund we agreed to disagree and they dropped the charges. Defending me against the federal felony charge [Operating a business without a license, up to five years in prison and a $250,000 fine] did end up costing us almost $300,000 of our retirement funds, our daughter's college fund, our savings, and the equity in our house.
You can read all about it here:
http://www.jmwagner.com/http://www.burtw.com/However, if you sell your Bitcoins though an exchange you will not run into this specific issue since there is really no way they can call it a business, go after you, and then grab all the assets they can get their money grubbing hands on.