Something that seems to have been added to SQL Server 2005 Enterprise Edition, very late in the development cycle, seems to be on of it's best features.
The ability to have one DB, located on SAN, available to multiple SQL Servers at the same time, as a read only DB is just incredible.
You can really scale out reporting, and might save you from having to flatten the data so that it is report friendly. Just throw more servers at the problem now. You need a bit of effort to update it, but it is really worth the while for those scenarios where data is loaded on a daily or weekly basis.
As long as your SAN can handle the throughput, it think it is a great feature.
The documentation in not in the SQL Server 2005 RTM BOL, but is available as a KB article: http://support.microsoft.com/?kbid=910378
Well done Microsoft!