Meaning, you might not get to run SQL Server AlwaysOn Availability groups on Windows Server 2012. If not, you'll have to check several patches are applied for it to work correctly on Windows Server 2008 R2.
This excellent resource provides a list of the needed patches in the FREE AlwaysOn Setup Checklist PDF.
I think the easiest way to determine if all the required patches are installed is by using the PowerShell cmdlet get-hotfix with the -computername and -id parameters.
Beware, the example below is a single line.
get-hotfix -computername YourServerNameHere -id KB2494036, KB2494162, KB2520235, KB2524478, KB2531907, KB2550886, KB2552040, KB2578103, KB2578113, KB2582281, KB2616514, KB2654347, KB2687741, KB976097, KB980915
If any of the patches are found, a five column result set is returned.
If all the patches are found, you'll see fifteen rows.
If none of the patches are found, the command throws an error and you'll see red.
|White beats red any day.|
Does that mean time moves faster when you blog? ;-D