This issue has been affecting our company since Safari 5.1/Lion were released. We are an HR/payroll company and in our new hire process we have lots of PDF's of government forms that we ask new employees to fill out and they need to post electronically back to our server. We haven't had any option for Mac users running current updates in a while.
This advisory says Adobe hopes to have a workaround by the end of the year. I hope that is true.
http://kb2.adobe.com/cps/908/cpsid_90885.php
In fact, I personally prefer to download a form to my local machine and then fill it out and submit from Acrobat/Reader.
Max Wyss.