If the person who answered this question is right, you cannot put a binding as the value in a setter in a style in Silverlight. Which is a shame, because I have 4 textblocks
In Silverlight: Well... yeah, you can't do a binding. Here I used a static resource, (which probably won't meet your needs). This is closest you are going to get without doing the bindings in code.
0.5
EDIT: Well, here it is in WPF anyway...
Here you go, in WPF:
Of course you can get a lot more creative than this. Also, depending on how / when / where your styles are defined, it is sometimes easier just to do it in code.