I've got a pressing need now to start testing the Z10, but I can't really do this until BES 10.1 is out (and of course 10.1 on the Z10 as well but I see that it's officialy out with the carrier Globe in the Philippines (we have an office there) so it will be probably be pushed soon from UK carriers as well where I reside).
It looks like other than possible 'during May' floating around forums like here there's no genuine release date ?.
I'll reach out to the carrier/provider we use in the UK but I realy doubt our account manager would have a clue about this.
Thanks.