I'm looking to see if there is a way to change the color of a textblock in silverlight on mouse over. I have tried a trigger which I read now doesn't work. I would like to avoid having to do it in the codebehind if at all possible.
Your instinct on not using code behind for that event is a good one. Allow me to sharpen it though: Don't change the visuals from code-behind, but allow your ViewModels/Code-Behind to own the visual state of the control.
The solution here is to encapsulate the specific visual changes in a custom visual state, and invoke that Visual State either from a ViewModel or a Blend EventTrigger & GoToStateAction.
To learn more about VisualStateManager I strongly recommend you watch these 4 "How Do I" videos by Steve White @ http://expression.microsoft.com/en-us/cc643423.aspx
To learn more about the GoToStateBehavior see @ Link