Plus Avalon just started shipping the first mining chip ( http://blog.zorinaq.com/?e=70 ). And they announced they will only accept bitcoins as payment for the 2nd batch of 500 units @ $1500 ea, which starts selling tomorrow... That potentially means people buying $750k worth of bitcoins for a batch that will sell out really quickly. This will surely push the exchange rate even higher than $20.
Edit: there is no resistance upward right now on MtGox. $300k of buys would push to $24. $500k to $30. http://bitcoincharts.com/markets/mtgoxUSD_depth.html