Though it's lacking some of the goodness of the same operation in MS Office applications, there IS a way to save PDF documents to a SharePoint document library directly from Adobe Acrobat 7.

The first thing you have to do is set up a new Network Place in My Network Places. To do this, open My Network Places, and click Add a network place.  Follow the Wizard, and in the Internet or Network Address field, enter the full URL to the SharePoint document library.  For example, http://sharepointserver/Shared Documents.

Then, in Adobe Acrobat, using the Save As dialog box, click My Network Places, and choose the Network Place you created.

This process won't prompt you for item properties (i.e. SharePoint columns), but it does allow you to get things into SharePoint right from Acrobat 7.