The RAS server is not a standard part of CR, it is part of "Crystal Server" comes with (I believe) the Developer edition of XI and I'm not sure which version of 2008.  I believe that Crystal Server will serve up reports to web users and get around the session issue.  However, the version that comes with Crystal has only 5 concurrent user licenses and you have to purchase more if you need them.  If you only have the 5, the 6th person who tries to open a report while 5 others are open will get an error message stating that there are no licenses available.  Also, there is, I believe, and 100 user limit in the number of concurrent licenses that can be installed.