Happy New Year to everyone! :)
This week I will provide distilled information about GeoClustering.
SQL Server Failover Clustering, which includes support for both local and multisite failover configurations, is designed to provide high availability and disaster recovery for SQL Server. The multisite failover clustering technology has been enhanced significantly in SQL Server 2012.
The one cardinal consideration to keep in mind with deploying all of these workloads on multi-site clustering is data replication. As opposed to local clusters, multi-site failover clusters share no central storage. Cluster data must be replicated and synchronized between all of the sites of a multi-site cluster. You will therefore need a third-party data replication solution. However, Windows Server 2008 takes care of the rest of the clustering needs (heartbeat monitoring, failover, etc.) in these deployment scenarios. Microsoft cannot provide or suggest methods to replicate the data between the remote sites.
Windows Failover Clustering is a prerequisite for implementing SQL Server Availability Groups, so the first reference should be these articles and whitepapers about Windows GeoCluster:
Requirements and Recommendations for a Multi-Site Failover Cluster
Microsoft Windows Multi-Site Failover Cluster Best Practices
Description of what to consider when you deploy Windows Server 2008 failover cluster nodes on different, routed subnets
Regarding SQLServer running on a GeoCluster: