It's already been officially released, along with a numer of other new processors from AMD, they're just really hard to find right now. Newegg just added some of the other new models over the past few days, I'd imagine they'll add the new 555 some time next week.
this CPu is available quite well, infact I bought 1 here in India on the 16th. it was available for a week before that. also most of the people giving out reviews of PII 555 are confirming that they were able to unlock the CPu to a Quad core including me. i ogt a stable B55 @ 3.6 GHz @ 1.35v. I am afraid to test over that due to lack of temprature readings . even in dual core mode the cpu runs hot @ 1.456v stock volt. had to undervolt right out of the box to get the temps under control. also the stock Fan is rampant, runs above 4000 RPM and thus is very noisy. infact if testing prime95 or other CPU intensive tests the fan was continously running @ 6000+ rpm.