Was Liberty Reserve’s shutdown an attempt by the U.S. to control digital or e-currencies, and how severely did it impact Bitcoin?

Jon Matonis would probably be the best person to answer this question. But, generally speaking, the US is trying to regulate and slowly mitigate Bitcoin based exchanges, asking that these exchanges get regulated and registered with FinCEN and then presumably the States will follow suit asking them to have a Money Transmitter license.

See: FinCEN's Virtual-Money Guidelines Add Roadblocks for New Companies