Since Microsoft announced they would be retiring their PIC (Public IM Connectivity) service, the ability to federate with AOL will soon cease to exist.  Interestingly though, AOL has made a public statement saying they will now support direct federation with Lync customers.

AOL is pleased to offer Microsoft Lync customers the opportunity to continue their current federation with AIM and establish new federations if needed. For the first time, we are enabling companies with the ability to establish a direct relationship with AOL to provision and manage their connectivity to the AIM network. This will also allow you to have direct and immediate access to AIM technical support engineers who can quickly identify and resolve any AIM-related issues, thus making the transition to AOL is seamless with no disruption to your company and users.

More details can be found on their website as well as an application to enable direct federation here: http://aimenterprise.aol.com/pic.php