CiviCRM 3.4.x and 4.0.x introduced API v3, a more consistent set of interfaces for integrating with CiviCRM using PHP, Smarty, Javascript, and REST. Building on this consistent core API, recent CiviCRM updates have introduced even more ways to manipulate your data -- such as chaining and CSV batch importing.

Thus, functions implemented according to the API v3 conventions can be invoked several different ways. If you would like to leverage this infrastructure for use with a new or customized API call, then download the latest release. With 3.4.6/4.0.6, external developers can expose API functions for new entities, new actions, and even generic actions.

CiviCRM 3.3 introduced a new hook that allows you to interact with and alter dedupe queries. Unfortunately, it was something of a "hidden hook" as it lacked documentation for quite a while. But it can be quite useful and powerful, and thus deserving of a review.
In version 3.3 and 3.4/4.0, the dedupe tools in CiviCRM received several notable improvements, including a restructuring of how the dedupe queries are built to improve performance, and the introduction of a paginated display with table caching that significantly improves the dedupe review and merging process. However, running a rule can still take quite some time on a large database (250k+ contacts), and the matching mechanism is quite basic -- simply comparing field data with field data.
That's where the dedupe hook can come into play.

Imagine for a moment that CiviCRM is a garden. In all its object oriented complexity lie bugs and weeds that need to be effectively discovered and managed. Managing a garden the size of CiviCRM is a daunting task for one individual, and even a team of developers along with a community of end-users and testers still need help. There is indeed help to be found! 

Hi,

Some improvements on permissions and the API are landing on 3.4.2 and 4.0.2.

On the previous versions, the permissions where not enforced (on php and smarty) and checked on the same permission "access civicrm" for the rest and ajax no matter the operation and entity.

Many modern web applications have a lot of spam deterrent such as Captcha, Bayesian filters, URL, ip detections etc. One example is trying to do 2 consecutive search on the CiviCRM.org forum and you will get a an error that look like

"Your last search was less than 5 seconds ago. Please try again later."

The concept behind this is flood control is to prevent a webbot (automated script) that is trying to spam and flood the server. 

I’m happy to announce the rebuilding of CiviCRM translation resources. If you’ve been a visitor to our Transifex page previously, you know that CiviCRM always ran two concurrent sets of translation resources – one for the stable version and one for the upcoming version (since its first beta release). This was cumbersome – and is the past now.

This new API is the recommended method to Create, Get, Delete or Update any CiviCRM data from your code or an external system. It is much more coherent and easier to use than the api v2.

It seems like time to give people a quick update as to what api v3 is about. API v3 will be shipping with CiviCRM 3.4 and basically it's like v2 but more so. Well, it's like bits of v2 api and all the other bits have been changed to be like those bits... make sense?

This is a summary of ideas from this forum topic, http://forum.civicrm.org/index.php?topic=15983 , and discussion should continue here.

I'm working on a CiviCRM/Drupal installation for an organization that puts on workshops and houses and feeds people for the duration of the workshops.  CiviCRM's built-in way of handling price sets as flat lists of options and prices, doesn't quite do what we want.

I have been working on dedupe optimization, part of 3.3 release and a make it happen project, and we are quite happy with the results. A fuzzy rule (first+last+email) which would take 4.3 mins on a 65K contact database, now takes 1.02 sec (tested on a iCore5, 4Gig machine). On a 1.45 million database same rule which used to take forever (i had to quit after 1 hr), now takes 13 sec. Below are some more stats.