A little late, but here is the web development news from the first half of December 2010.
The ECMAScript 5 standard has been approved, and it includes a strict mode features that repairs/removes some of the languages most problematic features:
YUI has announced the release of YUI 2.9.0 (probably the final version of YUI 2) and another preview release of YUI 3.3.0:
Mozilla and Opera disable WebSockets by default now that a security vulnerability has been found. Although it is not a fault in WebSockets themselves, buggy caching proxies were susceptible to cache poisoning: