I noticed that with my Nokia E61, Notes sync well enough from Outlook to the phone, but do not sync the other way around. So that if I write something in a note it won't be updated in Outlook.
I experimented some more and discovered that in order for something to sync back to Outlook from my E61, the note title (i.e. first line of the note) had to change. If i changed something in the body of the note (i.e. subsequent lines) it doesn't detect it as changed.