WordPress is an open source blog publishing application. WordPress is the official successor of b2\cafelog which was developed by Michel Valdrighi.
Documentation: Good documentation, which covers all aspect of using an customizing WordPres
Last releases: Wordpress has a stable codebase and releases is rather seldom
Client-side integration: jQuery and script,aculo.us are included in Wordpress package.
Community: Wordpress has several very active forums
Last releases: 2.7.1
Project example: DevSnippets
Drupal is an open source content management platform. Equipped with a powerful blend of features, Drupal supports a variety of websites ranging from personal weblogs to large community-driven websites.
Documentation: Drupal has a very strong documentation which includes lot of tutorials for newcomers and full API description.
Frequency of releases: The major releases of Drupal is rather seldom and coming out in one or two years.The minor and bugfix releases is coming out every two or three months.
Client-side integration: Drupal includes integrated jQuery library.
Community: Drupal community is large and active. You can ask you question on the Drupal forums or go thematical IRC channel to get live support.
Last releases: 6.10
Project example: iForm
Source : AjaxLine.Com