There are several issues here.
1) The N8x0 can wake themselves up, you can even set an alarm that makes an N8x0 boot itself, from power off, at the alarm time. So, hardware wise, the N8x0 may be even better than the Pandora in this respect - I haven't heard anyone describing such a feature for the Pandora. If it's there, nobody's been telling.
2) What you need, though, is software. And there's the rub. The N8x0s aren't working well as PIM devices because the software just isn't there. There's GPE calendar, and some other attempts, but to PDA users these fall short, unless your requirements are simple.
3) One reason software is easier on a Palm, for example, is that it has an operating system designed around the whole PIM concept. There's not a filesystem, and independently running programs and daemons, everything's just a set of databases and it's very easy to, say, link ToDo issues to the Calendar and Contacts. And link it all into the Alarm system.
4) Which doesn't mean it's impossible to do the same on a Pandora (or N8x0), it's just quite a bit more work. And you will probably have to create it as a complete suite, which is what GPE tries, and some others. They are just not very good at the moment, and they're a bit big and slow.
5) However, if your PIM requirements are covered by the limited functionality on the level of Google Calendar and the like, then that's not out of reach in the short term.
Tor