Hi Rene,
I remember some draft a while back but that was not from Bluetooth SIG. I believe it was a 6lowpan working group (http://tools.ietf.org/html/draft-ietf-6lowpan-btle-09). Or do you have another reference?
I checked the Bluetooth SIG Panorama (Summary of ongoing projects by SIG) and there are no traces of IPv6 from what I can see. I am not sure if Core improvements are mentioned here though.
Best Regards
