I play Vanilla, if it matters.

According to the UI, the keyboard shortcut for chopping forest or jungle is option-c. This doesn't work on either my iMac or my MBP. The workers sometimes move, but they don't chop. Does this shortcut work for anyone else? If not, is there a valid keyboard shortcut for chopping?

This question has been discussed before (http://forums.civfanatics.com/showthread.php?t=180281) (found with a Google search on "chop shortcut"). The conclusion then was that it should, and does, work for most people.

Post 8 and 9 of the thread cited by AlanH suggest that there is a problem for Intel iMac and MBP.

Post 12 suggested that opt commands worked for that poster's Intel iMac.

I'm assuming AlanH's "brain dead" Mac (as defined by Civ 4) is a PPC. (I have a hard time believing that any Intel Mac's specs are below Civ 4's requirements, although I gather some of Intel Mac's video cards may be too advanced for Civ 4.)

'm assuming AlanH's "brain dead" Mac (as defined by Civ 4) is a PPC.
Yes, that was back in the day. At that time I had a 1 GHz/1.2GByte G4 PPC with a Geforce 4MX which was well below the minimum requirements to run Civ4.

I've just tried it on my Mac Pro in Civ4 v1.74. and the shortcut doesn't work. So it looks like it's broken here.

PS. I tried running Cv4 1.74 in Rosetta, and the shortcut worked. So it seems it's a difference between PPC and Intel code.

Thanks. I did a little testing and opt-c does the "select all units on the same tile as the active unit" thingy on my machine, as mentioned in the other thread. So it seems like there are two shortcuts bound to this combination, one active on PPC and one active on intel.

Ahah! I tried other shortcuts to persuade it to chop, and failed, but didn't find out what Opt-C does do. Well spotted. Aspyr strikes again!

PS. I tried running Cv4 1.74 in Rosetta, and the shortcut worked. So it seems it's a difference between PPC and Intel code.

Why does Rosetta run PPC code?

That's what it's there for! Rosetta is the emulation layer that was provided as part of OS X when the switch to Intel occurred, so that all the existing PPC-only software would continue to operate. Until recently MS Office and Adobe Creative Suite were only available as PPC versions, so they could only run in Rosetta.

For any application that is delivered as a Universal Binary, containing both PPC and Intel code versions, an Intel Mac normally only runs the Intel-native version. However, you can use Get Info in the Finder to select the "Open in Rosetta" check box to force an Intel Mac to run the PPC code in Rosetta. I don't recommend it for Civ4 - it performs like a one legged pig on my Mac Pro, and I only did it to test for this difference.