The OWA package on http://www.cobb.uk.net/OWA can be used, in conjunction with the webdav package, to access documents on a Microsoft Exchange server using Outlook Web Access.
Included at that site is an example of using the OWA package to keep KNotes (a Linux PIM module that provides sticky notes) in sync with your Outlook Notes folder.
There is also (at the same location) an application using this package to provide IMAP clients with access to mail on an OWA server.
I have added an owaSync package which automatically keeps local copies of Notes, Calendar and Contacts folders in sync with the Exchange versions. It is only one-way sync at the moment (copying from Exchange to the local folders) but that is still useful. In particular this can be used to keep the KDE kontact application up to date with contacts, appointments and notes from Exchange.
I also use it to synchronise my Nokia 770 Internet tablet.