I make blendshape in maya and export to fbx can I use it in unity3 or How can I export it for use in unity3
You'll need to animate with bones - not blendshapes, morphs or vertex based animations.
http://unity3d.com/support/documentation/Manual/HOWTO-ImportObjectMaya.html
MegaFiers now has a Maya exporter for Blend Shapes making it very easy to add to your Unity project. Maya Blend Shapes in Unity with MegaFiers - YouTube
Previous answer is incorrect, there's a free script available that allows one-target morph. It's generally considered to be too slow for most applications but might be of good use for some simple stuff. Link below:
http://www.unifycommunity.com/wiki/index.php?title=MeshMorpher
Since 4.3 unity supports blendshapes directly, you can drag the FBX in.
To animate, you can use the faceshift plugin [1] for motion capture.