A little update. I just noticed on the Jef Raskin web site under the Archy FAQ, that the authors do intend to use the Command key as a replacement LEAP key. How about that.

Jef Raskin praised the merits of a LEAP key which could serve as something like the M-x, or C-s commands in Emacs. (I’ll take this opportunity to plug TextMate, an OS X app which uses C-s quite well.) In other words, he saw the need for a meta key, which the user could press, type in a command or formula, and then depress, allowing the computer to execute the command. At least one person appears to have missed the point on this one. As others point out, Blacktree’s Quicksilver does a fantastic job following through on its “act without doing” mantra. I recently figured out that if you use Apple’s Command key to activate the dialog box, you are granted the fantastic ability to LEAP around your filesystem. Here I come to save the day!