if your are lucky to be on old bootrom, then you have a chance to downgrade your baseband itself from 05.14.02 to 05.13 or 05.12.01 using fuzzyband tool in cydia. if you have upgraded to newer baseband 05.14.02 and in new bootrom above 5.08, then you are out of luck at the moment. wait for the unlock to be released. also sorces say, the unlock wont be released untill the release of iOS4.2. so might be a bit of wait.