The Isolates feature was intended to make it possible to run
child_process.fork() in a thread, rather than a full process.  The
justification was to make it cheaper to spin up new child node
instances, as well as allowing for fast message-passing using shared
memory in binary addons, while retaining the semantics of node's
child_process implementation by keeping them in completely isolated v8
instances.

It was a very informative experiment, but has ultimately turned out to
cause too much instability in node's internal functionality to justify
continuing with it at this time.  It requires a lot of complexity to
be added to libuv and node, and isn't likely to yield enough gains to
be worth the investment.

We're going to roll back the changes in master that were added to
support Isolates, and instead focus on Domains and other things that
promise to increase stability and make debugging easier.  This change
will land in 0.7.3.  It's entirely possible that we may decide to use
v8 isolates in some future version of node, but they will not be in
0.8.

If you were eagerly looking forward to using this feature, and find
yourself shocked or frustrated by this decision, please contact me
directly.  It's not our intention to leave anyone stuck, and I do
understand that this feature was promised for some time.  If this
causes hardship for you, let's figure out another way to get your use
cases handled.

It's never easy to back-pedal, but doing experimental things means
sometimes finding out that you were headed in the wrong direction.
The sooner we make this change, the easier it will be.

Thanks.