It looks like cheap stock prices are a gift from the bears. According to a weekly survey from the American Association of Individual Investors (AAII), bullish sentiment declined to its lowest point of the year (bespokeinvest). It seems that many people are too much concerned with Greece and other problems and they will miss the huge buying opportunities which result from the low valuations.
I reckon that the rally will continue because of cheap stock prices, rising profitability of companies, the continuing catch up race of China and other emerging markets and rapid technical progress (iPads et. al.).