Long time miner, new forum member.
The recent significant increase in a Bitcoin's value versus the US dollar may be related to online press coverage. Daily Reckoning has finally noticed Bitcoin and run a lengthy article on 3 June:
http://dailyreckoning.com/an-emerging-free-market-currency/Daily Reckoning's general world view is pro-gold, pro-silver, anti inflation and anti government intervention. It has a reasonably wide readership.