I sat the 70-680 test for WGU today and passed with a 836. I'm debating taking the 685 test in two weeks, though I will probably cave sometime tonight or tomorrow and schedule the test.
Because I have experience with many of the things covered by the test, even if just obliquely, I didn't think the test was too terribly hard. I can see it causing problems for people not familiar with AD or GP or some of the deployment tools. If anyone is planning on taking this as part of the MCITP:SA or EA, it might be a good idea to cover the server tech first and ease into this later (I know this has been mentioned many times on here but I just want to say it again).
I used the following resources to study for the test
Sybex 70-680 -
MCTS Windows 7 Configuration Study Guide: Exam 70-680 by William Panek
I thought this book was good. I would supplement it with another resource though.
Sybex 70-685/686 -
Windows 7 Desktop Support and Administration by Darril Gibson
This was a solid book. I highly recommend this on its own for the 685 and 686 tests or as a supplement for other material. And really how can you go wrong with a book from Gibson?
Sybex Mastering Win7 deployment -
Mastering Windows 7 Deployment by Aidan Finn, Darril Gibson, Kenneth van Surksum
Another really good book. Its focus is rather narrow, but it covers deployment in such detail you can't help but learn what you need along with much more. I read the WDS chapters twice and ended up making my WDS server at work much nicer.
Professor Messer's 70-680 videos -
Professor Messer's Microsoft 70-680 Certification Training
These were great. I would say that they were at least as good if not better than the comparable nuggets.
LabSim - This was what WGU uses. I didn't click with me and so I didn't like it. It was personal rather than an actual problem with it (LabSim seemed to cover everything necessary and ask a lot of tough questions to reinforce what is being taught). What I did do with it was only what my mentor required. YMMV
And the Google/TechNet combo to round things off. Great resources to study up on weak areas or check on little things.
Next up for me is a possible 685 test (I will know for sure in a day or two) and the CCNA as that is what I have on deck at WGU come September and my new semester.