The hotfix for enabling case-sensitive URL's to be crawled with MOSS is pretty well known http://support.microsoft.com/kb/932619 (The fix is also included in MOSS SP1) but what is maybe less well known is that you also need to enable the same registry key in Search Server 2008 to crawl case-sensitive URLs - i.e. it's not switched on by default in MSS. This is also true after installing SP1 for MOSS, you'll need to set the registry key afterwards to enable the fix.
Following the KB article enables case-sensitive crawling, it doesn't enable case-sensitive searching. So for example, MOSS and MSS will be able to successfully crawl and index a URL of http://SERVER/Site/content but a query of "QUERY TERMS" will return the same results as a query of "query terms".
Richard Riley Senior Technical Product Manager Microsoft Corp