Breaking Changes
Through 2.x, if Buffer.concat is invoked with a single element array, then it will simply return the first element from it. But, starting from 3.0.0, irrespective of the number of elements in the array, a new Buffer object will be created and returned.
Through 2.x, the the dgram socket.send() method emitted errors when a DNS lookup failed, even when a callback was provided. Starting from 3.0.0, if a callback is provided, no error event will be emitted.
Refs: #1796
The upgrade from V8 4.1 to 4.2 will require a recompile of all native add-ons. (The API surface area has not changed significantly, so most add-ons will "just work" after a recompile.)
os.tmpdir() has been changed to never return a trailing slash regardless of the host platform.
