I think that Joomla has incredible capabilities with component and 3rd party integrations. I disagree with wordpress, plone, or drupal being better platforms in most cases. Joomla is extremely extensible, and security is manageable. Joomla 1.6 is soon to be a reality and many users will have incredible tools available with just the need to implement anything to acoomplish nearly any information based goal. Extension development is definitely in it's infancy having the last 25% of the extensions developed in the last 8 months or so. by the end of 2009, it wouldn't surprise me to see 10,000 open-source extensions. The true money-maker for extension developers is to find customers who need even more functionality in already existing modules, plugins, components, etc. In the coming years we should begin to see a higher quality of extension integration with site content. As well as the increase in extension specific addons.