There probably is not a way to extract the voicemails into a DB like you would Exchange, or rather search the DB in CUC for a paticular voicemail.  If you want to store the wav file from a user, you can use IMAP to access the subscribers account, download the voicemails and save the wav file.  You may also use the PCA in CUC to get to the voicemail you want.

The only thing you can see is who its from in the subject if the info passed from CUCM or the PBX.  (caller ID or another subscribers name).  Of course, CUC can not tell you the content of the voicemail unless you listen to it.

In CUC 8.0 I hear there will be voice to txt app that will translate the voicemail to txt.