Americans United has a piece by Rob Boston on this. So does the Baptist Joint Committee. Here's a quote from the latter:
Pray in church; pray in your own home; pray privately anywhere you like, or gather in public spaces and pray: in the park, outside the courthouse, around the flagpole before or after school; but the very last place to expect a solemn religious evocation is at an official government exercise. If you demand one, you'll get what you are asking for: a circus. People of faith should instead demand the opposite: don't sully religion by using the state to promote it. No more government-sponsored prayer.