STR: 1. Visit the password calculator in the URL field of this bug. 2. Enter 'aaa' and 'aaa' for the first two fields. 3. Click the little arrow-button to calculate a deterministic password in the third field. 4. Toggle methodjit.content in about:config 5. Click the little arrow-button again, watch the supposedly-deterministic password value change to some new value. Something's afoot. Tthe non-JM version is the right one. Mozilla/5.0 (Windows NT 6.1; WOW64; rv:2.0b6pre) Gecko/20100911 Firefox/4.0b6pre Updated moments ago.
Appears to have been fixed overnight. Gecko/20100912 behaves ok. Closing. (I'll reopen if it stops working again; I use that page regularly, so..)