AdSense Management API is now open to all AdSense Publishers. Previously AdSense Host API was available and open to websites with over 100,000 daily page views. AdSense Host API is still available for the websites with over 100,000 daily page views, side by side Google has launched AdSense Management API on 27th October.
In AdSense Management API: a primer blog, S?rgio Gomes of AdSense API Team has promised to add more features to AdSense Management API. So, we can expect some more features in future.
Background of AdSense Management API
Like many others, we personally disliked the fact that AdSense API is only available to websites with 100,000 daily page views. For some niche blogs, despite good revenue, it is quite impossible to reach 100,000 daily page views. Moreover, it might fluctuate, actually one needs a bit more pageviews. Pageviews should not be an metrics to restrict a developer to use and experiment on certain features.
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Is there are new moves for AdSense ?
Seems so! Google AdSense earlier has introduced some points which made it more tougher to be a Publisher, then the Color Palette feature has been added and now this AdSense Management API.
What is AdSense Management API ?
“The API provides the full set of AdSense reporting functionality available in the AdSense interface, with a wide array of dimensions and metrics, configurable sorting, and powerful filters.”
AdSense account and Google Code account must have to be of the same account. In other words, if you have AdSense account with a different login, you need to open a Google account. That is not very hard. Java, Python and our beloved PHP libraries are available as usually. You can generate and Manage Ad Codes from scratch as well.

Create Account Call can be done now, Currency code is available as well – that means reporting can be done in local currency. The features mentioned within the strike-through text are not available from AdSense Management API?publicly (Thanks to T.John for the correction, kindly see comments.)
It is definitely a good move. We have not deployed ours, but will do soon. It will be easier to develop WordPress plugins as most of the developers basically never gets over 100,000 daily page views.

Generate Ad codes, currency and create account functions are available only in AdSense Host API and not in AdSense Management API.
(Edited, URLs towards own website removed.)
Yes John, the Generate Ad codes, currency and create account functions of AdSense Management API are not available publicly. Thank you for bringing the attention. Post will be edited along with mentioning you (will be available after the cache is cleared).