For the second time, Fedora 13 release schedule will be postponed for about one week due to unresolved showstopper bugs on their bug tracker. The official announcement was made by Paul W. Frields. The record of the Go/No-Go meeting can be found here.
I think it's better to have this release schedule in order to get the best user experience when using Linux rather than forcing them to do unusual things, just like what Ubuntu developers did with 10.04 LTS due to last-minute bug. More over, it's LTS version which should be more stable since it will be used by many users around the world due to long term support.
That's why Slackware never set a fixed date on release plan. It will be released when it's ready and the decision is made by Patrick himself. He knows when will the next release is stable enough to be consumed by public
I'm still waiting for the next Slackware 13.1 to be released this year (hopefully in June or worst case July).