A lot of traders and multi-billion dollar hedge funds buy and sell on gossip and speculation, so yeah, this kind of thing does have an impact on price.
AAPL stock is down because of three things 1) there is no way WWDC could have lived up to the hype that had built up beforehand 2) the overall market is trending down lately and 3) the rumors about Steve Jobs's health.
There are many times when a catalyst is obvious. In this case AAPL's recent fall cannot be attributed to the broad market. Apple was riding high during the past few months while the rest of the market was in the doldrums.
A lot of people are worried for a number of reasons, and therefore they are taking profits in AAPL.