Is RC4 a problem for password-based authentication?
By George, you're on to something.

To answer the question you asked, I don't know of anyone actually attempting to recover a password this way, or it even being discussed.  However, it does appear to be feasible, given enough encrypted streams.

How many are enough?  Well, I've started running a few simulations; preliminary results indicate that with perhaps 2 billion encrypted streams that encode the same password, the attacker may be able to deduce enough information to narrow possible passwords to a reasonably small set.

I'll update this answer as I get more precise information on the number of streams needed; however, I've seen enough to be fairly confident that this attack can work.

UPDATE

I have experimentally verified the fact that you can decrypt RC4 if you get the same message encrypted enough times, albeit with somewhat more than I suggested above.  In particular, I encrypted a 16 character password using RC4/DROP-512.  With 8 billion encrypted messages (with the RC4 key for each message being chosen randomly and independently), I was able to successfully recover the exact password by analyzing the statistics for the streams.

I'll be writing up an eprint article detailing my observations.