What is new?
Taken from the blender release page
Cycles Render Engine
A number of new features were added, including render layers and passes, multi GPU rendering and selection of GPU device, improved sampling for complex environment maps, border rendering, BVH caching for faster rendering of camera fly-throughs, and new shading nodes for color correction and a checkerboard texture node.
Many new UV editing tools were added: an advanced interactive stitch tool, to align and join together UV islands. A subdivision surface aware UV unwrapping to reduce stretching. Seam marking in the UV editor, and a tool to compute seams for islands. Sculpting tools to grab UVs and relax or pinch unwraps.
The Remesh modifier is a tool for generating new mesh topology based on an input surface. The output follows the surface curvature of the input, but its topology is a uniform distribution of quads. It can generate smoothed output or tag sharp features to better capture corners.
A Second Life compatibility option was added for exporting armatures, along with a number of other fixes related to transformations and armatures. There is also a new development team that will try to improve the Collada integration further in following releases.
Other new features include: improved bump map quality in the viewport, various new dynamic paint options, international text copy and paste and editing in the text editor, longer names and file paths, drag and drop parenting in the outliner, new theme's preset system and many more changes.
Object tracking support has been added, so that not only camera animation can be reconstructed from footage, but also the animation or transformation of objects in the scene. This comes along with many improvements to the tracking user interface and tools.
The boolean modifier now uses the Carve library, which should give much improved results. This library is more stable and faster, resolving old well-known limitations of our previous library. The general workflow and options available in the user interface are unchanged, usually the modifier will simply run faster and produces a better output mesh. However there also some changes in behavior.
The game engine user interface was polished, editing text objects in the user interface and through the python API has been made easier, full screen and antialiased rendering has been improved, along with various other changes.
Matrices and vectors math classes were improved in various ways. Column-major access was changed to more standard row-major access and easier access for rows, columns, translation was added. Vectors now can have arbitrary size, and matrices are now pretty printed in the console.
Network render now has support for version control systems, render engines, point cache baking jobs, and a new web interface was added, along with a number of other improvements. There were also features added to After Effects export, X3D export, Atomic Blender PDB import, MHX import, UV layout export, and Screencast Keys.
As usual, each release includes a long list of bug fixes. For Blender 2.62, we have fixed 205 bugs in existing features.