I've been hearing this for a long time, but the "taper" isn't really a taper in all markets. In consumer markets, yes the taper is very real. Infact I bet you could take one $500 machine off the shelf of Wal-Mart every year for the past 5 years and benchmark them all within 15% of each other overall.

But it isn't really visible when money is no object. If it's not the cores getting faster it's the core-count going up. Moore's Law is really easy to beat if you focus on making your CPU die's larger instead of their transistors smaller.