In AC0.71, once you uploaded your attachment for a discussion item (message, or comment), it would give you a new upload field. AC1.0 only gives one upload field. Is there any way to attach several files to a message under 1.0?
One of the improvements that will be available in activeCollab 1.0.4 is the ability to manage comment attachments (first message in a discussion is actually a comment). Using this page you can add as many attachments to a comment as you wish.