Nice. I can see you have at least two of the same widgets I have (Weather and Calendar). I don't see WebRep's little green bar indicator though. Have you moved it down to the notification bar at the bottom? I don't think having iGoogle as my home page is the trigger though. I am beginning to suspect that, as Dieselman points out, that it may be an interaction between two of my add-ons. I have another add-on called 'RedirectRemover' that has caused several of my normally clickable links to stop functioning unless I turn it off.
What happens to my gadgets is this: When I approach the little drop-down in the title bar of the gadget, it 'dims out' and does not allow the drop-down menu (Edit, Delete, etc.) to appear. I also cannot 'grab' the title bar and move the gadget to another position on the page.
If you are able to do this, with WebRep enabled, then there is something not entirely correct somewhere; but, I have five computers, all with updated versions of FF to 4.0 and ALL of them exhibit this same behavior. If it was just one, then I'd look on that computer for the problem, but since it's on all five of them.... (2 Win7, 2 Vista and 1 XP/SP3)
As I said before, I have the perfect opportunity to test all our theories out this afternoon with a perfectly clean install of FF4.0 on a laptop that has never seen Firefox before. That should tell the tale.