Hi,
Imho the querying of apps, event reporting, and undertaking of actions is a must for a hacker device like the n900, and all applications should have the appropriate interfaces in place to support it. Actually I assumed something like this would be in place in maemo by default.
Some people said "isn't this a bit like option foo in program bar", but they are missing the point: something like this gives you total control to do whatever you want, depending on anything. configuration options are much more limiting, they cannot express the same level of flexibility.
Also, if you centralize the "brain" of the scheduling and event handling, you can make a lot of apps simpler, and better.

Personally I'm quite curious about the GUI approach. My first thought was that the semantics are too complicated to be expressed in a GUI (and hence, I would opt for letting users write in a script language)
However, if all plugins present their properties and events in a uniform manner, it may be possible to come up with a decent enough GUI that lets users easily write logic ("at this point in time, query this variable from program foo, if it equals bar, then wait this amount of time, then do this action, etc")

Btw, for scheduling, there is also the 'at' tool (atd) which may be a better choice then sleeping. although i'm not sure how exactly it's implemented.