Terminal does not appear in launcher

I had the same problem. The terminal did not show up in the Laucher or when using Alt+Tab. This was after migrating my Ubuntu 12.04 installation to a new laptop.

Solution: Uninstall gnome-terminal using Ubuntu software center and re-install it right afterwards.

Yeah, it is a bug of some systems. Read it here. Maybe there can be other work around to it. I will post it tomorrow, if that is so.
Maybe the weather applet is causing the problem. If then, just give a try to cut the weather applet from the conf file under .config/cairo-dock/current_theme everything may work fine.

I was having similar problems. I couldn't consistently get the terminal to show up in the dock, and even if it did, it might not show up via Alt+Tab, or clicking the icon might not do anything or might create a new terminal window rather than switching to an existing one. Here's how I finally managed to "fix" it:

1. Create an executable shell script file containing just the following:

   #!/bin/bash
   gnome-terminal
   

2. Create a .desktop file linked to that shell script; I did this by running gnome-desktop-item-edit /usr/share/applications/gterm.desktop from inside a terminal window (you need the gnome-panel package; if you need further instructions, you should be able to find them by Googling "gnome-desktop-item-edit").

3. Open the directory containing the .desktop file, and run it by double-clicking. (You might need to first make sure you don't have any terminal windows open.) You should see an icon for it appear in the dock. Right-click on that icon and select "Lock to Launcher".

You should now have a properly working dock icon for your terminal. Apparently the fact that it's running a shell script, rather than running the terminal command directly, gets around whatever was causing the problems.

If anyone has a cleaner solution, I would love to see it. But unless and until that happens, I hope this method can at least help people get things working properly on the surface.

EDIT: After going through all this, I did something that required a reboot. After the reboot, there was an icon for the actual Terminal in the dock, in addition to the one for the shell script I had created. Both icons seem to work how I would want them to, so I've deleted the shell script one. So a reboot might be all that's needed. I'll leave the shell script method here in case anyone can't get this working just by rebooting.