This makes me think that there are really two types of scheduled tasks in Drupal; those that need to happen even if the site is inactive (sending a mail queue), and those that only need to happen if people are visiting the site. Poormans cron does a great job of the latter, but can't guarantee the former on a low-traffic site. An elaborate but potentially very useful (and user-friendly) route to take would be to make this distinction and introduce a hook_tasks or something similar to complement cron. This would basically be the poormans cron module reimplemented to call hook_tasks instead of hook_cron. Thus we could use cron for stuff that really needs it (mail, backups) and hook_task for stuff that *has to work* with or without cron, and is only relevant when somebody is looking at the site. Thus, the aggregator feeds could be run on hook_task. Jeff Eaton wrote:
This is a GREAT idea. It's worth noting that most other CMS systems, including WordPress, do this in their administration sections. The only trick, I think, is Aggregator.module's dependence on cron. Until a user configures that bit of the system, they won't get any security announcements.
--Jeff