Yes, Firefox latest update is not going to be it’s version 3.1. Generally a 0.1 version upgrade is released as a maintenance release. However, some additional features have been added to the update. Developers at Mozzilla have suggested to name this version to Firefox 3.5 to reflect the many important changes being incorporated in in this version. Check the Firefox developer meeting notes

What’s new in firefox 3.5?

• Improved JavaScript engine
• New privacy features
• Improved tab handling
• Enhanced web standards compatibility

Anyway, Firefox 3.1 is not dead. The next beta release is going to be Firefox 3.1beta3. There are questions being raised if this is just a game to delay the next release. It doesn’t matter with the numbering of the version to most of us. An upgrade with new features is always welcome. The quicker, the better.