You can begin to feel the energy slow down in the market. I've been watching the trading in China's Shanghai Index, and it finally traded lower today (about 0.5%). Former fed chairman Alan Greenspan made comments that their market will correct. He wasn't exactly going on on a limb in that statement, but it did catch the attention of a lot of investors.
One thing to remember is that weaker markets typcially open higher, and work their way down the rest of the day.
I think that the rest of '07 still has the potential to be a good year for investors, but I think short term, most likely during the summer months, we'll see a slower trend.