I've heard repeatedly that XCode's integration with SVN is lacking, but seeing as I have personally never used it, I cannot help but wonder why.
Now I'm starting a new project, and once again SCM has come up. This time though, I think I want a better idea of what exactly XCode does and doesn't do right with SVN.
So, have any horror stories?
A total non-answer to what you're asking but...
I'm a real big fan of Versions (www.versionsapp.com) and its made me not care an ounce about any XCode integration with SVN.
No horror stories: I've been using XCode 3.1.2 with SVN for almost a year now and it's good enough. The XCode SCM (Source Control Manager) is quite basic, but stable. The only thing it does not do well is removing a file. When you delete a file, XCode will offer to remove the file from version control as well, but when it's time to commit it will complain that the file is missing. So I generally do an 'svn rm' from the terminal to remove a file, rather than deleting it from within the XCode Files & Groups panel. If I forgot and svn keeps fussing, 'svn cleanup' usually sorts it out.
It doesn't show you progress while commiting or checking-out. Also if there is a project file conflict then you are given options either to keep it or replace by latest copy. Either way somebody's changes are lost.
Apart of that SVN integration is pretty usable - we rely on that for several months.
Personally, the teams of developers I've worked with have never regretted switching from svn to git (sorry, Stack Overflow won't let me put in the link) or bzr (http://www.bazaar-vcs.org/). You might look into them, although I don't know much about XCode integration. (Everyone I know has been a command line junkie -- or used TortiseBZR, etc. on Windows.)