The Bubbletop Widget Platform is about to launch their beta site and open it up to developers according to an invitation they have sent out.
From their email:
Sounds fun. Note that the site still says alpha.
They are also holding several events, including a c0ding c4mp (c00l!), to generate widget developer interest for Bubbletop.
This is the same group that is behind Pikeo. It all looks promising, well thought out, and nicely designed. I am interested to find out to what degree they are offering a full fledged widget environment and how it differs from what is out there already. They did mention a social component...