Yes I think 90210 refers to the Beverly Hills postcode, symbolic of the glitzy lifestyle Domino enjoyed (or rather didn't) before she chucked it all in. I still keep thinking of Boba Fett when I read 'Bounty Hunter' though.
As for the contemporary thing, The Jacket is now set after the Gulf War, I believe, so that's early '90s. The original script had it set during Vietnam.
But Domino will be Keira's second consecutive title role, with P & P, and her third if you include PoThieves.