I wrote a small Zenworks NAL app that pushes out Adobe Reader 8 to network users. I used the Adobe customization wizard 8 to create the Microsoft MST Transform files that modify the Adobe Reader MSI file. Then I deployed the MSI in Zenworks in conjunction with the modified MST. Check out msiwisdom for more details.
[added June 8, 2007]
Aaron has released customized transform files for Adobe Reader 8.1. I for one appreciate all the hard work he did, this sure makes my deployment easier.