BitPay (a less feature-rich Stripe for Bitcoin) claims to be processing more than $1 million USD in transactions per day.
It's hard to get a sense of how large the world of Bitcoin is, and especially hard to get a handle on the amount used for commerce vs. speculation. BitPay is one of the main merchant processing companies so this statistic is one worth paying attention to.
BitPay raised $30 million in VC funding a little while ago. It's currently valued at around $200 million.