It may be, but it doesn't solve some of the problems that cputhrottle does. My main use for cputhrottle is to limit the CPU usage of Flash. It's not that I want to use the CPU for something else, at least not at the moment, but I don't want my laptop's fans to turn on, the whole thing to heat up and it to kill my battery life. [re]nice will only allow another process to get CPU priority, it won't keep the CPU utilization low.
The bizarre part, when it comes to Flash, is that I've yet to see an actual difference in the application behavior when I throttle down it's CPU usage. I would think that if it normally maxes out 7 of my 8 logical cores, being limited to 40% of one core would make introduce slowness. But I guess that's just an indication of how poorly written the OS X flash client it.