I don't know how big the threat from ID is (Clive's earlier question) but I've been struck by how mixed the views of trainee science teachers on my course are about this. For example one young woman told me she was relieved to be teaching chemistry and not biology because she was worried about offending students when teaching evolution. She's an atheist but felt that it would be wrong to 'impose' evolution over and above their personal beliefs. I found this shocking but perhaps it shows that the ID 'movement' are successful in this insidious approach of 'respecting everyone's beliefs'.
So if some science teachers need persuading that evolution should be taught as 'true' rather than just another point of view then that suggests there is a real threat.