All else being equal, the more people who use Bitcoin (whether as a store of value or medium of exchange), the greater the demand for it -- and therefore the higher its price, because the supply is fixed.
This means that in the long run, Bitcoin's price will be positively correlated with its adoption.[1]
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[1] My full thoughts on the matter: http://cs702.wordpress.com/2011/05/29/on-the-potential-adopt...
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 $30. http://bitcoincharts.com/markets/mtgoxUSD_depth.html
Bitcoin has speculative bubbles, fraud, robberies, money laundering, gambling, and Ponzi schemes. I think that takes care of all the qualifications for a real currency. Am I missing anything? :)
It would be interesting to compare BtC not only to the USD, but also to a bag of currencies, to see if it relates to a USD devaluation 'compared to the rest' (usually JPY, EUR, GBP)
Your title isn't clear, and it's not even February yet, so I assume you meant "over the last year".
Anyone else think this looks like the Gartner Hype cycle? http://en.wikipedia.org/wiki/Hype_cycle
Maybe I need to get back in to bitcoin mining...
Plug for my "fastest way to lookup bitcoin price" website:
Liquidity is the major issue for the foreseeable future.
Waiting for tokenadult to repost his Bitcoin comment: https://www.google.com/search?q=site%3Anews.ycombinator.com+...
In all seriousness though, there is one interesting thing that is different now from last time. Last time being the previous frenzied Bitcoin price hype bubble that peaked at 31$. No one fears that Bitcoin will crash to 0/pennies anymore once the price stops climbing, at least not due to standard market forces. It's pretty well established now that there is some baseline demand that will form a price bottom (assuming no large network attack occurs). What effect that will have on this bubble (if one forms) is hard to say but it should be interesting and not a repeat of last time.