The trend could be exponential, which would be the mathematical expectation. An exponential fit gives a R2 (goodness of fit) of 0.94 (very good fit). If the exponential trend were to be maintained, by May 7 there should be over 4,000 confirmed cases of Swine flu in the US. If this prediction fails, it could be an indication that containment measures are having an effect. We'll see.
Update 5/7/2009
I've continued to follow the count of confirmed cases in the US. While it didn't go into the thousands by May 7, an exponential model continues to fit the series quite well.
While cases have reportedly plateaued in Mexico, the same is not true of the US just yet.