The next best thing is the incremental search of the menu bar, where you get the cursor up onto the menu bar and type the first part of the menu you want, hit enter when it highlights the correct target, then incrementally search for the leaf item you want. Rinse and repeat. The only problem is the shortcut key to get up to the menubar: CTRL-F2, which is cumbersome on my laptop.
I'd rather light a candle than curse darkness, so I remapped it to CTRL-ALT-APPLE-SPACE (which are all together). This sounds like a horror, but it's really easy, and that combination wasn't taken by anything I can find. Until Quicksilver fixes the application proxy stuff, this is the next best thing.
Virtually instant update: Apparently Jason was sitting with his computer on, hitting the refresh button over and over on this blog, because he posted this comment almost before I finished the first entry. This link shows how to use a help hotkey for an alphabetized, incrementally searchable list of menu command in Leopard via the new help system. I added it here in case the comment didn't get read by everyone. Thanks, Jason!