We already spoke about the soon to launch dual-core Deneb with two disabled cores, and AMD now calls this CPU Callisto. To make things better, Callisto 45nm dual-core got its official name and spec.
Callisto will launch in late Q2 2009 under the Phenom II X2 550 brand, and this top speed SKU will work at 3.1GHz and will have 7MB of cache total. If you think about this CPU as Deneb with two cores disabled, you will learn that this CPU will have 2x512KB L2 cache and the whole 6MB L3 cache.
This CPU is after Intel's Core 2 Duo generation and it might not be winning against the 3.33GHz clocked Core 2 Duo E8600, but we are sure that Phenom II X2 550 will win the price performance battle as it definitely comes cheaper than €200 at launch, probably closer to €100. As you can read below, we told you back in February that this interesting part is coming.