So basically, according to the article, the the Xbox360 CPU is a derivative of the Cell power core?
The Power core is derived from an earlier research processor originally done in 1997/98 and updated in 2000 called GuTS.
The control and Integer processing portions of the 2 cores appear to be identical.
The important part in the XBox is the VMX units, the Cache and the interconnect between them. These parts are either not present in the Cell's PPE or are different (e.g. the PPE has standard VMX, the XBox has an enhanced version).
They both have cache locking but this is also present in other PowerPCs (G3, G4).
The PPE may also appear in a separate IBM product (embedded processor).