Sometimes. Vudu has carried a few. I'm not sure who else might have. They're generally only available for purchase, not for rental.
I end up buying the discs from the UK. With one or two exceptions (Ratatouille comes to mind), they're region free, and usually cheaper than what Disney wants for the streaming version - and higher quality too.
Ratatouille 3D is the only Disney 3D (incl Pixar/Marvel/Lucasfilm) to date that is region locked.
This doesn't included items like Need for Speed and The BFG which weren't distributed by Disney in some countries, but there are even 3D versions of both of those that are Region Free in other countries (or from the Asian or Mexico/Brazil Region A releases). Ratatouille 3D is the exception there in that it was never released anywhere other than FR/DE/UK