Surely Iambic will release a version of Agendus for the Pre at some time. Personally, it's one of the programs I can't do without. To get an idea of what it probably will look like, check out the screen shots for the latest version of Agendus for iphone at:
iambic.com/agendus/iphone/whatsnew.asp
(Sorry this is not posted as a link, but apparently you must have a minimum number of posts before you can post links)