Is it possible to have 2 or more databases active, and synchronized between them?
SQL Server scales up not out
HA/DR is separate to scaling
Replication is not designed to publish entire databases
Replication or mirroring add an overhead that defeats your scaling out
Merge replication will have conflicts at some point


Personally, I'd buy a bigger server, go Enterprise x64 edition, and wait for SQL Server 2012 HADRON