The best answer I've been able to find at this point is "some time this summer". I'll get back with more detail when I receive it.
Check here for the site for student version download:
I've been told that the ST6 Student Edition will be available as soon as all the languages are released for ST6, which will be completed in August. You should be able to expect that the student download of ST6 will be available by September 1.
Is ST6 already available for students and high schools?
We have some schools that registered in SE High School pogram in the Summer and they are starting their classes, so if ST6 is already available, it would be great if they can use it right away.