Why can't I get Startup Manager to appear?

If you're using a wired keyboard, plug it directly into a built-in USB port on the Mac, not into a hub.

If you hold the option key down too early, it's ignored. Press Option when you hear the startup tone and hold until the logo with pinwheel.

Third-party wireless keyboards may not work. Third-party Bluetooth adapters almost certainly won't work.

If all else fails, select the boot volume you want in the Startup Disk preference pane. You'll have to change the setting again to go back to your usual boot.

mmellon wrote:

...the boot disk that I made(from the Lion installer) is booting into recovery.

It doesn't actually boot throught to my desktop...

Of course not, it's a Lion installer, not Lion. 🙂

Lion is too big to fit on a DVD

If you want Lion on a external boot drive, you need to clone or this

Create a data recovery, undelete boot drive

Most commonly used backup methods explained

Thank you!

I just got a hub today, but thought an over enthusiastic run with Onyx had messed up my system files

Sticking the keyboard directly into the desktop solved my access to Startup Manager immediately.

KEYBOARD PLUGGED INTO A USB HUB, INSTEAD OF DIRECTLY INTO THE COMPUTER . . . WAS THE PROBLEM!
THANK YOU Linc Davis!
That's exactly what was causing NONE of my Startup key options to work — not the Option key (opens Startup Manager window), not the Shift key (Startup in Safe Mode), not the Option-Cmd-P-R keys (resets the NVRAM, called PRAM on pre-Intel Macs), nor the Cmd-R keys (opens up Recovery HD window).
I had recently added a USB hub to my Mac Pro 1,1 (built in Nov 2007), and hooked my keyboard up to that USB hub.

After reading your comment, I removed the keyboard plug from the USB hub, and hooked it directly to my computer.
VOILÁ! PROBLEM SOLVED. Thank you, thank you, thank you!