http://microsoftgadgets.com/Blogs/gadgetnews/archive/2006/05/25/5857.aspx
Also: http://gallery.microsoft.com
These were both released or updated pretty quietly over the holiday weekend.
I like that there is a centralized location for all of this, but I don't really care for the fact that Gadgets should work the same across both Web and Vista Sidebar. It seems that most of what we will get will be gadgets that aggregate data. or gadgets for little games, but you get almost no access to the local machine. I use Desktop Sidebar (http://www.desktopsidebar.com) and it seems like it'll be infinitely more capable because it has acess to machine level functions instead of a few APIs (Power Level might be nice for a laptop, but CPU Usaage isn't very useful without a process list, etc...) According to this URL, there are a few system functions you can access, but without real machine level access, I think a lot of the power/worth of sidebar gadgets will be lost.
(The only web site based gadget I have is weather.com, the rest are for control of my local machine, or accessing local data, like controlling Windows Media Player, or Windows Live Messenger contact list)
Of course, I could be missing something, hopefully there will be better samples soon.
(As an aside, there is no tag for Windows Live itself in the tag list for Community Server. That seems like a bit of an oversight)