Here's a brain dump of possible options I see for 3.2rc2:

    1. document and do nothing
        -> IDLE (and other tkinter program) crashes whenever a user types a composing character (like Option u in US layout for an umlaut) when the 64-/32-bit installer is used

    2. don't ship the OS X 64-bit installer, only the traditional 32-bit one
        
    3a. don't ship IDLE.app and bin/idle with 64-bit installer
        
    3b. don't ship tkinter, IDLE.app, and bin/idle with 64-bit installer
        
    4. for 64-bit installer, link tkinter with Aqua Tk 8.4, like 32-bit installer
        -> no tkinter available in (default) 64-bit mode, users would need to force 32-bit execution
        -> need to fix IDLE to only run in 32-bit mode
        
    5a. for 64-bit installer, link tkinter with a third-party X11 Tk 8.5, most likely MacPorts
        -> X11 version works in both 64- and 32- and is likely more widely tested (on Unixes). MacPorts for example currently supplies an X11 Tk by default.
        -> non-native look and feel
        -> is X11 installed by default on 10.6? (check and document)
        -> MacPorts currently does not supply binary packages so users would need to install Xcode developer tools

    5b. for 64-bit installer, have the installer build an X11 Tk 8.5 (using the installer's existing third-party lib infrastructure) and ship with the 64-bit installer
        -> same as 5a except that IDLE and tkinter would now work out of the box but at the cost of the additional unknown development and testing work to get Tk built with the installer

At the moment, for 3.2rc2 my inclination is to pursue option 4 and at least explore the feasibility of option 5b with a fallback to option 3a while encouraging (but not depending) on a future fix for Cocoa Tk. Again, this applies only to the 64-/32-bit installer; the traditional 32-bit installer is linked with Carbon Tk 8.4 which does not have this problem.

Post 3.2, I think it makes sense to pursue a previously-discussed option to support multiple Tk versions with one release so users can choose.  That would also have the potential benefit of making Tk 8.5 available in one form or another for users of earlier OS X releases.  But that's a matter for later exploration.