What does it mean when there is almost no "Volume" like that? Yet the price goes way up?
UPDATE: does it matter if there's a combined chart? The price is also just gox.... so the volume is just gox ...
The reason it matters should be fairly obvious. Say there is an exchange with 5% of the volume of Gox. The price will still be roughly the same! Simply because of arbitrage with other exchanges. In Bitcoin world, a spread of 8-12% might not be uncommon, but it's not like they're wildly running in opposite directions.
So a price of $375 on an exchange with a tiny amount of volume compared to April is not a bad sign if, say, there is another exchange with a more reasonable amount of volume (i.e. all gox's volume are belong to China) compared to April and the same or similar price.
In order to accurately judge volume over time against the price, in a situation such as this where exchange volume has shifted quite significantly since April, we'd have to see combined volume, virtually regardless of which exchange's price we were using.
So we might look at Gox volume now vs april, and we look at BTCchina and BitStamp volume now vs. April. Now we can see why there is a problem with just looking at the volume of one exchange over such a long time period! Then we look at all the other exchanges too. Then the fucking permabear peanut gallery starts piping in "But China has 0% trading so their volume is fake, and therefore their price is fake, and chinese fake all their statistics, and BTCChina doesn't even exist, and blah blah blah, and blah blah blah."
Oh, peanut gallery.
EDIT: Oh, and since I opened the Volume can of worms - The combined volume chart @ Bitcoinity covers all known online exchanges - but there is also the possibility that a lot of the "big money" that has been entering Bitcoin has been doing so via other avenues. One could say that this would eventually be reflected in the major exchanges, but not necessarily. Big investors might find the resources to buy directly from miners ('clean coin' concerns) and this volume might not find its way to the exchanges. Then the miners would have less to sell to the exchanges, lowering supply, and supply and demand, blah blah blah. OTOH, this might be insignificant. But don't dismiss either high or low volume without considering all possibilities.