While in SQL 2005 we had to install IIS as a prerequisite to reporting services and its reports. in SQL 2008 its no longer needed.

what ? why ? how ? what should I do ? I need IIS !

yes. you do, probably for the OpsMgr’s web console, but first, what did happen to the IIS prerequisite ? – well, SSRS 2008 use the HTTP.sys directly to handle the web part, it has no need in IIS anymore for generating reports. that’s fair, but if you want to IIS and SSRS 2008 co-exist on the same server you have to install the IIS first and after that the SSRS because they both uses port 80 by default ; IIS use it by the Default Web Site and SSRS use it to it’s /reports.

to resolve this problem as I already wrote, install the IIS before SSRS then open the SSRS configuration (Microsoft Server 2008 ->  Configuration Tools -> Reporting Services Configuration Manager) and set precedence rules and URL reservations. List of this precedence rules and URL reservations can be found in here.