For our purposes that's everybody. When the bubble popped my dad told me on the phone he did read about "those bitcoins" and "how huge they have become" in the newspaper.
On that day I saw two teenagers on the street following the bitcoin price on their androids. ("216 Euro!!!")
They all learned what Bitcoin is all about: Buy and sell bitcoins.
People with any sort of tech literacy have heard about Bitcoins at this stage. I have friends in Argentina that are not the most tech literate and they certainly know about it. Anyone who may actually use it anytime soon knows about it.
It's difficult not to flip-flop when it comes to the valuation. Predicting pricing action has very little to with fundamentals. It's all about the perception of fundamentals and predicting whether or not there will be another wave of speculation based on headlines. If all of the business that now use Bitcoin had quietly adopted, we would not have seen much of a stir in the price.
If a wave of new buyers is coming in, it is because they think there will be a successive wave of buyers based on upcoming news and announcements and they are still getting in relatively early. It has nothing to do with the number of downloads, companies using Bitcoin, widespread adoption, or any new deep level of understanding of Bitcoin. It has everything to do with the fact that there could still be a news release around the corner that can propel this higher visàvis speculators.
I've been surprised by recent pricing action. Everything tells me that this should trade sideways to down over the next few months. But....it's not the new adopters that are setting this market. It's the new speculators, I suppose. And I suppose that regardless of the fundamentals, for the foreseeable future there will be the allure that some big news story might propel this into bubble territory again. We should retest $50 but I'm not sure how soon/if this will happen.