Case solved!
Apparently the problem was the case-sensitive formatting of the hard drive. After formatting the hard drive and reinstalling Snow Leopard everything works brilliantly!
Thank you!

Haha you were right about the case-sensitive vs insensitive. I'm not entirely sure how this happened but mine is case sensitive, which probably explains certain things.. I will try a clean reinstall of Snow Leopard one more time with the regular insensitive option and see if I have more luck. Looks like I'm in for the night. Again...
But thanks for your help!

YES! That's the exact one I'm getting! And also no leftside toolbars.
This is what I have in that folder on a fresh install..

Thanks!
However, if that is the list then I've already tried it unfortunately. Any other suggestions? It seems as if any kind of extension and plugin is broken from the very beginning.

Yes, the window is broken directly after a fresh install (I uninstalled by deleting app.support, preferences and program files). The same happens with a clean install of Sketchup 7.1 (free version). Could there be any hidden settings files that I might not know about? Is there a complete list of files related to Sketchup somewhere which I can check? Just to be sure..

No, it begin with updating to Snow Leopard. I tried to reinstall Podium just now but nothing changed unfortunately.

Thanks for the reply..
Yes, I'm aware, and the files are there, both the files I manually copied and also the pre-installed sandbox extensions etc. So the files are installed simultaneously in both locations, the problem is that none of them still actually loads when I fire up the program..

I might also add that Podium is also not loading after installation...

I really don't get this. After upgrading my mac with a clean install of Snow Leopard and reinstalling Sketchup Pro 7, suddenly it won't load any ruby scripts regardless of where they are placed, and also the preferences -> extensions window is also completely empty!
I've tried to create Tools and Plugins folders in the User -> Library - > App. Support etc folder but then Sketchup just loads with "cannot load" errors on all scripts... Any suggestions? I'm getting rather desperate.