I've been holding off upgrading my Subversion repository and tools, until last week or so when the "perfect storm" of source control arrived: VisualSVN Server with Subversion 1.5, TortoiseSVN 1.5, and the last piece of the puzzle, AnkhSVN 2.0.
If, like me, you've been waiting for the right time to upgrade your Subversion source control to the newly-released 1.5, then the free VisualSVN Server is one official (and dead-simple) way to do this as CodeBetter's James Kovacs recently noted. My older 1.3 repository was upgraded painlessly using VisualSVN Server, although I could have also called svnadmin upgrade from a command line...