Who are the industry leading widget developers / vendors / etc?

If you are referring to platform vendors, I think most popular are Yahoo Widgets (ex Konfabulator), then Microsoft Vista Gadgets, then probably Dashboard, DesktopX, Opera and Google Gadgets.

About widget developers... I guess there is a few thousands of us only here at widgipedia :-)

The top cross-platform widget system is clearspring

Are you sure about clearspring?? take a look at google: [www.google.com]
This is a joke on clearspring site about 'Widgets Served: 4,150,617,631'

...i just found that: 7.2 Billion Widget served !!! Clearspring is very busy !

I would say Dashboard are the most popular as they are "the original" ones and have been out there for ages and come by default in every single Mac. However, not many people use mac though...
then Yahoo & Google are doing quite well, better than Opera & Vista (because Vista hasn't spread that much yet...)
I wouldn't compare DesktopX with them but I would say there are tools (including DesktopX) that create "platform-less" widgets (my favourites) that don't require installation
Clearspring? what's that?

salut!

:: Games Garden ::

I use dashboard regularly and am completely pleased with it. But about the sales I don't have any idea.