Ensign Paris notes in the forums that MacOSRumors updates with hints at much to come:
Well, if a Dual 1GHz model with 133MHz SDRAM doesn't impress you, how about a Dual 1.4GHz beast employing powerful new PowerPC 7500 processors and screamingly fast 400MHz RapidIO-compatible memory?
According to MOSR, due at Apple's mid-year update.