If your organization does, than it might run into an issue with Note items either disappearing or being moved to the archive mailbox of a user unexpectedly.
In order to see these issues a few Exchange 2010 pre-requisites must be setup:
1)Exchange 2010 SP1 must be in use
a) Functionality changed in SP1 so the Notes folder is now processed Messaging Records Management (MRM)
b) In RTM the Notes folder was not processed
2) Default Policy Tags (DPTs) or Retention Policy Tags (RPTs) must be in use
a) See Understanding Retention Tags and Retention Policies for more information on these
3) DPTs and\or RPTs must be included in a Retention Policy
4) Note items must meet the criteria of the DPT or RPTs
5) A Retention Policy, that includes the DPTs and\or RPTs must be applied to mailboxes
If the above pre-requisites are in place then items in the Notes folder can be deleted or moved to a user’s archive mailbox, depending if items meet the DPT and/or a RPT criteria.
To prevent DPTs from affecting Notes an Exchange administrator can create a policy tag that disabled the deletion action of Notes items. But as of this writing there is no administrator action that can prevent Notes from being archived if the RPTs are in use and Note items meet their criteria.
To prevent RTPs from being applied to Note items, end-users must apply the “Never” policy to the items or folders that contain them using OWA. This can’t be done in Outlook 2010.
For more information see the Prevent archiving of items in a default folder in Exchange 2010 EHLO blog post from 8/5/2011.
Finally there a bug in Outlook 2010 that prevents the opening of Note and others items from the search results against an archive mailbox. The hotfix in KB2544027, released 7/11/2011 for Outlook 2011, fixes this issue and related ones.