Can someone confirm or deny?
"The esc (Escape) key doesn't seem to be working correctly in the Terminal or iTerm. If you open a document vim foo and then go into edit mode (the i key), the esc key should put you back into command mode. The bug happens locally or via an ssh session to other machines, it also is happening on different terminal applications, so I believe that the esc key code itself is getting filtered at the OS level. (MacBook Pro 2,2)"
http://guides.macrumors.com/Mac_OS_X_10.5.2_Fixes,_Bugs_and_Problems
"The esc (Escape) key doesn't seem to be working correctly in the Terminal or iTerm. If you open a document vim foo and then go into edit mode (the i key), the esc key should put you back into command mode. The bug happens locally or via an ssh session to other machines, it also is happening on different terminal applications, so I believe that the esc key code itself is getting filtered at the OS level. (MacBook Pro 2,2)"
http://guides.macrumors.com/Mac_OS_X_10.5.2_Fixes,_Bugs_and_Problems