Mozilla have released the first beta of Firefox 4 that features the new 'JaegerMonkey' JavaScript engine.

On supported hardware, this beta of Firefox will automatically use Direct2D in an attempt to accelerate the display of content on graphically-dense websites. It also comes with a new HTTP Strict Transport Security security protocol, which insists that Firefox always uses secures connections. A new audio API exposes the raw audio data housed within the <video> and <audio> elements in HTML5.