I just read this on a blog about RainDrop - http://www.webmonkey.com/blog/Mozilla_s_Raindrop_Wants_to_Solve_Your_Communication_Woes
It is not a widget but a script and it is still in baby mode. So guess what, you will encounter bugs. I personally like Firefox - it rocks! But anyway, I do like how Firefox is taking this step to integrate the social media experience on your browser. Rather nifty. I will use it. What about you?