It seems like a very grey area.
My gut feel was that SSRS 'service' is what constitutes installing, but then you can never be too sure with Microsoft!
I haven't got 2008 server instance to look at, but on my 2005 Production server, which also runs 2005 SSRS, in the license file
'C:\Program Files\Microsoft SQL Server\90\EULA\License_STD_ENU.txt'
it definitely states (bold highlighting my own)
c. Running Instances of the
Additional Software. You may run or
otherwise use any number of instances
of additional software listed below on
any number of devices. You may use
additional software only with the
server software directly, or
indirectly through other additional
software.
- Analysis Services Shared Tools
- Business Intelligence Development Studio
- SQL Server 2005 Books Online
- Connectivity Components
- Legacy Components
- Management Tools
- Notification Services Client Components
- Reporting Services Report Manager
- Reporting Services Shared Tools
- SQL Server 2005 Shared Tools
- Software Development Kit
- SQLXML Client Features
- SQL Server Mobile Server Tools
so from that it would suggest that I can run SSRS Report Manager on another server, without needing a license
I would suggest checking out your EULA/License file
And if that isn't clear ask Microsoft!
Kev
UPDATE
The SQL 2008 page here http://www.microsoft.com/sqlserver/2008/en/us/licensing-faq.aspx
and in the FAQ
Q. Do I need a separate license to run the SQL Server tools and analysis services?
A. No, a separate license is not required. However, any device that has SQL Server tools or technologies installed must have a valid SQL Server license.
I guess it comes back to this definition of 'installed'