Determine the architecture of a Mac from the command line or script?

Problem

I'm writing a shell script, and I need to know the architecture, i.e. PPC or Intel. Back in the day, there was a program that told you, but my Mac doesn't seem to have it. Is there an easy way I can do this? for something in a log file? Call some other program that spits that out as a side effect? It would be nice to know what OS version I'm running too, but that may not be necessary.