Popfly is the fun, easy way to build and share mashups, gadgets, Web pages, and applications. Popfly consists of two parts:
1. Popfly Creator is a set of online visual tools for building Web pages and mashups.
2. Space is an online community of creators where you can host, share, rate, comment and even remix creations from other Popfly users.
You need to register for this right now, and though I have not been able to access it yet, this seems to be a way that MS hopes to popularize SilverLight