As I mentioned in the first paragraph, the tool is able to create custom firmware files for iOS 4.1 without needing to upgrade your baseband, as the result you can further unlock your iOS 4.1 firmware in 05.13.04 baseband using the version of Ultrasn0w.
Sn0wbreeze 2.1 works with the following iDevices:
- iPhone 4, 3GS, 3G
- iPod touch 4G, 3G, 2G
- iPad (on iOS 3.2.2)
- Apple TV 2G