2. In the resulting window, click the "More Info..." button. This will open the System Settings window.
3. Scroll to the bottom of that window and click "System Report."
4. In the left side of the resulting window, under "Software," click "Applications." This will provide a list of installed applications. One of the columns for sorting is "Kind"; all apps that are x86 will be listed with the kind, "Intel."
Funny, that didn't occur to me at all. :-/ Maybe that's because I'm used to the FHS and I expected a path starting with /System to be either a path that is interpreted by some command or a description of an UI flow, not a path in the file system. So the thing you would type in the shell is just '/System/Applications/Utilities/System Information.app'? Does the Finder support starting programs by typing the path in the pathbar, like MS Explorer on Windows?
2. In the resulting window, click the "More Info..." button. This will open the System Settings window.
3. Scroll to the bottom of that window and click "System Report."
4. In the left side of the resulting window, under "Software," click "Applications." This will provide a list of installed applications. One of the columns for sorting is "Kind"; all apps that are x86 will be listed with the kind, "Intel."