Trends are an interesting thing. Sometimes they can help you see the patterns of the past and guess what the future might be. They also have inflection points. An interesting one just occurred at Real Clear Politics. For the longest time Romney was below 10% in the nationwide polls. McCain has been steadily coming down from the 25% of days gone by. In the last few days their lines have crossed. Romney is now closing in on a slowly declining Thompson.

http://www.realclearpolitics.com/epolls/2008/president/us/republican_presidential_nomination-192.html