Whenever I try to access SSRS 2008 R2 through a URL (i.e. after being published on the net), it always shows a login prompt when accessing the report. The problem does not appea
I am assuming the prompt is for the username / password for the domain. Internally you are likely getting through the AD authentication check in your application as you will have permissions to deliver the report (you can test that premise with Firefox or other browser that doesnt handle AD authentication like IE does/
I think you may have setup for basic authorisation to view the report RSReportServer.config rather than web.config is that what you have done? (see this to see example http://msdn.microsoft.com/en-us/library/cc281309.aspx.)
If you are trying to get full anonymous access then you are in for some fun; luckily one of the RS team blogged a way to achieve it; I wouldn't advocate doing it straight onto a production box though.
http://blogs.msdn.com/b/jameswu/archive/2008/07/15/anonymous-access-in-sql-rs-2008.aspx