Ok, it looks like there are a few issues with SP1. This is a Microsoft problem, and not a Netapp issue. I originally misunderstood that the problems in question were using Hyper-V with Netapp Storage.
This list is not a comprehensive list, and I encourage all of you to check back with the site.
The biggest one that I see is hotfix 2263829, where hte network connection of a running Hyper-V virtual machine may be lost under heavy outgoing network traffic on a computer that is running Windows Server 2008 R2 SP1.
I can't seem to find an "official list" from Microsoft. But, I did find this great blog that details some of the problems:
Of course, these may not affect all of you, and therefore testing is crucial. Read all of the docs, know about the known issues, and proceed carefully! Hope this helps all of you out, and saves you some time.