@RTK - are you able to write to the Plugins folder now? That is, have you attempted to place or replace/update plugins to that folder yet? I was given a denied error even login as administrator...
Had to give the folder write privileges to all again to correct the error...
I did not have to give write permissions to the folder, however I do all of my updates manually as opposed to automatically since FTP is blocked at the firewall level where I have my server hosted.
Unfortunately none of the solutions described above that involve changing cPanel settings or changing PHP extensions to run under PHP 5.x only help me. I host a Windows Server 2008 R2 server using the latest PHP 5 myself, not through a hosting company, so unless the new WordPress doesn't like some of the default PHP extensions enabled in my PHP.ini (HIHGLY doubtful seeing as how I'm sure they QA their changes against a fairly defualt PHP installation), then those suggestions don't resolve this issue.
The only true workaround I've found is to do as I described earlier and give the IUSR user write permissions on my wp-content directory. This is the only solution (and I hesitate to even call it a solution) I've found for my setup.