What is the status/eta of this pull request? Unless integration is eminent we'd be willing to offer a bounty to help accelerate it's release. We really need this feature, our current workaround involving multiple bitcoind instances, and relaunch rescan per user session is catastrophically cumbersome.
Maybe one bitcoind handling multiple (separately encrypted) wallets would even better suit your needs? I'd chip in on that too.
Any word on how realistic that would be?