I'm looking into the 2012 feature, AlwaysOn. My instance for data warehouses will be 2012. However the source instances are 2008 R2. I'm assuming that I can't use AlwaysOn to keep my warehouses refreshed with current data from the production databases, is that correct?
Currently I use snapshot replication to update the warehouse twice a day but I'm looking for an option that gives more real-time data.
AlwaysOn isn't a solution for a data warehouse, but especially since you have 2012 and 2008 R2. The AlwaysOn databases will be SQL Server 2012 mirrored databases. So you can't have any schema changes like you would with a data warehouse. What you get with AlwaysOn is an identical database either real-time (synchronous) or with some latency (async).
How about transactional replication? That's what I used in the past for our reporting instance. We did switch to AlwaysOn when we upgraded to SQL Server 2012, but it's because our reporting database had the exact same structure.