We have a test system built with Windows Server 2008 64-bit Standard edition.
We're about to create a production environment. Aside from the guidance that it is a good idea to keep test and live as closely sync'd as possible, is there any reason to, or not to, install Windows Server 2008 R2 64-bit standard edition instead?
This is for 2 SharePoint farms, running on 10 VM's, with 24 cores and roughly 128GB of memory in total.
I haven't yet taken the plunge, but I'm anxious to get my HyperV servers bumped up to R2 for the virtualization performance improvements I've been reading about. You didn't mention whether you're using that or VMWare, but I suspect you'll be happy down the line if you deal with the R2 upgrade now, rather than after it's in production.
I'd do it now, but I don't think you're shooting yourself in the foot if you don't.
It's a bit rah-rah-MS, but informative.
Here is the link to Microsoft's official "whats new in Windows 2008 R2" document:
http://www.microsoft.com/windowsserver2008/en/us/whats-new.aspx
I think the biggest change affecting SharePoint would be the upgrade to IIS 7.5, but so far I haven't really seen much of a difference.