When configuring a new audience in SharePoint 2010 you can use an AD security group or distribution list to define your audience. Sometimes though the DL does not show in the list when you want to select it as source.
First thing to check is that the DL\Group is selected in your User Profile Sync configuration
Secondly some blogs refer to the Global\Universal and DL\Security Group settings in AD. To be honest I’ve tried all the different options and they all seem to work
The setting that worked for me was the “Managed By” property on the DL. If this is set then it looks like the DL is not pulled through to the audience configurations i.e. you cannot select it. I removed the owner on my DL, ran a incremental profile sync and it worked from there.