The OpenLayers 2.12 library for dynamic web maps is available:
OpenLayers 2.12 offers great new features and improvements in various areas:
A new CSS-customizable zoom control.
Sensible projection defaults to ease the creation and configuration of maps.
Tile caching for offline use.
CSS-based tile animation.
Improved image request management (tile queue).
Fractional zooming for tiled layers (a.k.a. client zoom).
Books on the topic