Hello Rohit,
(Most of) Our official client libraries have already been updated to
work with the new release, v200906. They're available from
http://code.google.com/apis/adwords/docs/clients.html
The PHP and Ruby client libraries are still being worked on, and
should be released in the near future. I'd recommend that you use one
of the official client libraries rather than standalone sample code,
as you'll have a much better development experience. If you do want to
see standalone code for v200906, though, you can find it linked to
from the bottom of the page mentioned above.
"Change history" functionality is something we pre-announced as a
v2009 feature in our initial Sandbox announcement:
http://adwordsapi.blogspot.com/2009/04/hello-all-as-we-mentioned-in-our.html
It has not yet been implemented as of v200906, and my understanding is
that it remains on the list of forthcoming features.
There's no specific method for performing recursive updates native to
the v2009 API. You'd still have to implement logic for determining
what objects to update in your code. As mentioned in our v2009 Launch
blog post, asynchronous calls have not yet been implemented.
What you refer to as dynamic keyword insertion is not a feature of
the AdWords API, but rather of the basic AdWords system. I don't have
any information about future plans for additional features.
The current release of v2009 is considered beta. I don't have any
information to share about if and when it will be marked as final,
though I can say that many iterations of the legacy API were
officially considered beta but were still used in production systems.
Cheers,
-Jeff Posnick, AdWords API Team