I recently took part in the Ludum Dare 48 hour game challenge, number 17. Here's my list of blog entries at the Ludum Dare site.
I didn't finish a game, but it gave me a chance to experiment some more with writing games in pure Javascript in the browser. I consider the final product a reasonable proof of concept of a Sprite() class which uses div tags with background-images. I'll probably develop it some more and put it into jsGameSoup. I really need to do a speed test on various platforms, and between using div tags and canvas.drawImage.
Here is a link to the tech demo, which has only been tested in recent versions of Firefox, but probably works in webkit browsers too. The world is procedurally generated using perlin noise on the server side, and a seedable MWS number generator on the client side for placement of trees and stuff.
Here is a link to the source code. There is a working bzr branch repository in the tarfile, as well as the source code itself.
I recently started working on the multiplayer code for Infinite8BitPlatformer, so hopefully there will be a playable multiplayer demo in the not-too-distant future. What I have working is test-client connecting to the server and getting a unique ID back.