pingVision

One of the interesting new opportunities - and thus pitfalls until you understand them - is Drupal 6's built in block caching. As a developer, I'm generally used to creating hook_block by just specifying the 'info' data in hook_block, and letting the other options be set by the admin via the blocks page. However, you can't set the caching level there, and more troublesome, you can't change the caching level of a block once it's been put into your site.