Turn into Phenom II X4 with the touch of ACC.
While pictures of the highly anticipated "Propus" core - the quad-core without L3 cache - have surfaced, it seems AMD is releasing early samples of the Athlon II X4 620 and 630 processors with a "Deneb" core, the same that has been shipping in Phenom II X4 900/800, Phenom II X3 700 and AMD Phenom II X2 processors.
As with all the previous processors based on the "Deneb" core, they can be unlocked to an X3 or X4 processor, if the silicon is in good shape.
In this situation, what is unlocked are the 6MB of L3 cache. The future Athlon II X3 might also allow for the unlocking of the extra core, besides the L3 cache, if we ever see "Deneb" based versions.
The unlocked Athlon II X4, caught in the Xtreme Systems Forums:
The extra 6MB of L3 cache allows for better performance in highly multithreaded applications, as the processor can synchronize data between the cores in L3 cache, instead of going to the system's memory.
The unlocking process is fairly simple and can be done following the steps on this post.
It's not expected that AMD continues to deliver "Deneb" based Athlon II processors into the future, but instead switch to the "Propus" core, which is cheaper to manufacture. This is a similar move to the introduction of the new Athlon II X2 cores that feature 1MB of L2 cache, compared to the previous Phenom X2 7000 processors, which also were based on the "Barcelona" quad-core dies.
The Athlon II X4 620 is expected to be priced at around 85eur.
Update: Unlocked Athlon II X4 620 benchmarks