Detailed Product list updated regularly by the product groups
Hot Topics for DST changes in 2007 (includes nice flow chart)
Another site with a detailed product list and guidance on process for DST
As far as the top issues go, I would say the biggest one is the fix for WSS 3.0 which another major University ran into during their rollout.
Windows SharePoint Services 3.0
There are also updates for all versions of Windows (including Vista) located at http://support.microsoft.com/kb/933360
Lastly, there is a live meeting being held for customers this Friday, below is the info if you want to include it in the customer email.
A Daylight Savings Time Update LiveMeeting event will be held on Friday, Sept 14th, 2007 @ 9am PST:. Please feel free to attend this meeting to learn more about the DST event for Q3/Q4 2007:
Click the meeting URL: https://www.livemeeting.com/cc/lmevents/join?id=msft091407sa&role=attend&pw=AGT732or
if you can’t click the above meeting URL, click the following link: https://www.livemeeting.com/cc/lmevents
When you click on either URL, the Join Meeting page appears. In the following fields, verify or enter this information:
Name: (Enter your first and last name)
Meeting ID: msft091407sa
Meeting Key: AGT732