The crowd has spoken and the SQL Server Team has answered! Denali is the first version of SQL Server to support the cross subnet failover feature first introduced in Windows Server 2008 Failover Clustering. It seems like we have been waiting forever for the SQL team to support this feature but the wait is finally drawing to an end.
The following is a link to a 5 minute video that demonstrates a 3-node cluster Denali cluster with two nodes in the primary datacenter and one node in the DR site in a separate subnet.
I will be demonstrating this solution at Tech-Ed 2011 in Atlanta this week. Stop by the SIOS Technology booth and have a look for yourself at the SQL Server Denali multisite cluster demonstration using SteelEye DataKeeper.