As of SAP Web AS 6.20 the ABAP report RSUSR008_009_NEW (transaction S_BCE_68002111) has been made available in SAP.
This report combines the (quite useless!) old reports RSUSR008 and RSUSR009 and had has become a simple but reliable tool to import your SoD rule set and to report on it.
It's possible to report on sole 'authorization id' (Critical Authorizations) or on a combination of 2 different 'authorization id's' (SoD).
For both reports you can create various reporting variants and you can colorize the various results.
Reporting is only possible on userids, so when checking your authorization concept itself, it is necessary to create dummy users per role (in a development system e.g.).
The possible granularity of the checks is equal with all the existing tools on the market: apart from checking on transaction codes, you can check on every object value and adequate AND/OR operators are available.
It is not possible to downdrill in your report and to make detailed analyses of the cause of the conflict. 'Heavy users' will still have to rely on the third-party tools for detailed analysis, but when you make a start with SoD reporting this tool can be of great use!
Here you can find the SAP Help for this report.
I also made an instruction with various screenprints on how to implement critical authorizations, combinations and report variants.