Linus wants a new terminal to pop up when he hits the terminal icon? That's pretty old-school behavior. OSX and Windows have long moved away from it. I don't use Gnome3, but hitting cmd+n or cmd+t when I want a new terminal doesn't seem to bother me much.
Linus is right. "Old school" or no, a new window for apps like terminal is exactly the right behavior. At least for my workflow it is: I want a shell right now, and I'll throw it away when I'm done.
I worked around this by binding Ctrl-Alt-T to spawn a gnome-terminal (likewise Ctrl-Alt-E to launch a new emacs window). Happily that key customization UI survived the transition to gnome 3.
Here's the kicker: there isn't one right way to make it work. Gnome 3 is basically changing to fit with how other recent desktop environments have behaved like OS X. Of course people will bitch but it's no less right or wrong. Maybe just unpolished.
Both terminal and iTerm require a right click to spawn a new terminal for me. I'd love it if I could left click the dock icon and get a new terminal with my hom directory as the working directory.
tell application "Terminal"
activate
do script ""
end tell
3. Save as an Application (probably in your Application folder)
4. (optional) replace the icon by ctrl-clicking the new Application and selecting "Show Package Contents". Navigate to Contents >> Resources and change the applet.icns to something more pleasing. Maybe copy the actual terminal icon.
5. put this icon in your doc and always get a new window when clicking it.
I spent a few years using OS X, and clicking on some corner of some terminal somewhere and hitting Cmd-N to get myself a fresh terminal (or clicking somewhere on the desktop and hitting Cmd-N to get a fresh file-manager window) was so convenient that even in GNOME 3 I have Super-N bound to 'new terminal window'.
Only items permanently pinned to the task bar exhibit this behavior. Pinning an item to the task bar (where running applications are displayed) just keeps its icon there permanently. On the other hand, in the start menu (perhaps similar to the activity menu? I haven't used Gnome3 with this new set up, yet.) even the pinned and recently used items, when clicked, open a new application.
Perhaps I misunderstood what the OP had an issue with. I perceived it as, when you attempt to run an application from a large, collective menu of all applications, if an instance is running, it would go to that instance, instead of starting a new one. This is not the way it is in Windows.*
If the OP declared that clicking a running application opened the running application, then yes, that has been the way it is for a while now, but it was that way in Gnome2, so I suspect this is not the case.
re: Windows and OSX moving away from it - really? Apart from some exceptions on Win7 clicking an icon brings up a new instance. Exceptions like media player are...exceptions, and at the application's discretion. Unless I'm mis-understanding something you're saying.