Yikes. Got me :).
All these new and cool e-mail features do not support attachements as of now, or, more precise, I did not test it yet, but i would be surprised if it worked with attachements. If someone can take a look at the incoming e-mails and run them through mime::whatever to get the attachments, that would be awesome, as you could then add the file to the CR as well (parent_id = sender_id or group_id, depending on what you are doing) and have this file linked from teh mail tracking as well.
Searching those e-mails is a piece of cake with mail-tracking. I am sure some search wizards can quickly write an indexer for the acs_mail_log table and store this in mail-tracking (please!).