I just installed the Daisy dock (from the Ubuntu repos), and it won't launch anything. I'm on KDE 4.4b2, and it won't launch the apps that already had launchers or the ones I dragged and dropped onto the dock.

Is Daisy dock a GNOME application? Can you provide a screenshot of it?

Daisy is a plasma widget. I'll fire up virtualbox in a bit to get a screenshot.

There's also a circular dock

Ah.... looks nice. If it previously worked under KDE 4.3, but no longer does under 4.4 Beta, I suggest you ask the author of the widget, who is likely located on kde-apps.org or kde-look.org.

Before doing that however, open Konsole, and run "kbuildsycoca4 --noincremental" then logout of KDE and back in.

I don't know if it worked under 4.3, I only installed it under 4.4

After ensuring the method you used to install KDE from is as recent as possible ( refresh the repository ) check that you have the latest versions installed, then remove and re-add Daisy. If it doesn't work still, I suggest filing a bug with its developer, who can likely be found on kde-apps.org as Daisy does not ship with KDE.