Microsoft begins accepting Bitcoin payments for Xbox games, apps, and Windows software through a partnership with BitPay. One of the largest companies in the world acknowledging Bitcoin as a payment method -- at a time when BTC was trading around $350, deep in the post-Mt. Gox bear market. Microsoft's move signaled that major corporations were willing to integrate Bitcoin despite the price downturn, lending credibility when the community needed it most.
Wikipedia: History of Bitcoin