Drupal 7, the latest upgrade to the popular open source web content management system, is now generally available, Drupal builders said on Wednesday.

Drupal powers millions of web sites and applications including WhiteHouse.gov and InfoWorld.com.  Better usability is a primary focus of version 7, which has been in development for three years, said Drupal founder Dries Buytaert. "We contracted with some of the world's best usability experts and we paid them for work on Drupal 7 usability for six months,"  said Buytaert, who is chief technology officer at Acquia, which provides commercial-grade support for Drupal.

Version 7 features improvements for users of Drupal-based sites as well so for site maintainers and site developers.  "We re-architected the entire back end system," boosting capabilities for visual design, navigation, and nomenclature, Buytaert said. Capabilities like more inline editing and WYSIWYG functionality have been added.  

"You'll be able to build much bigger web sites with Drupal 7 than people have done with Drupal 6," said Buytaert. But Drupal 7 might actually be slower than version 6 in some instances. "Pieces of the site might be slower, other pieces might be faster," Buytaert said. "In general, it's going to be more scalable."

Also featured is improved databases support, including a new database abstraction layer. Better Postgres support is featured along with SQLIte backing. Image management has been improved as well. "It's much easier to add images to content now," Buytaert said. It will be easier to generate thumbnails, handle different image styling, and handle private files. Additionally a built-in automated test environment is featured in the release.

Drupal 7 user Examiner.com, a news and information site, attracts more than 22.4 million monthly unique visitors. An official at the company lauded the upgrade, noting Examiner.com switched from ColdFusion to Drupal 7.

"Drupal 7 allows you to engage in pluggable architecture and what that allows you to do is things like make use of much faster databases like MongoDB," said the official, Matthew Saunders, Examiner.com director of technology. The CMS has been "designed with the idea that enterprise users will be able to make use of the software," Saunders said.

Upgrading from Drupal 6 to Drupa7 requires execution of an upgrade script. Users may have to rewrite some code for custom modules and also update for API changes.

The platform "has really started to take in the last couple of years," Buytaert said. Drupal founders also are basing the cloud-based version of the CMS, Drupal Gardens, on Drupal 7. So far, 30,000 sites have been built on Drupal Gardens, Buytaert said.

Drupal followers on Friday will gather at more than 260 "release parties" in 900 different countries to laud the release of version 7, said Buytaert.