"Firefox 1.0.5 is a security update that is part of our ongoing program to provide a safe Internet experience for our customers. We recommend that all users upgrade to this latest version."
From what I hear, they didn't plan any more updates ahead of the 1.1 release, but several security issues came up. The frame injection spoofing regression got the most press, but the release notes only rank its severity as "moderate". There are two "critical" and four "high" severity vulnerabilities fixed in this release. So this actually fixes more holes than the last one, which involved three "critical" fixes.