Apple has posted the first beta of iOS 7 for developers to download.
The build number is 11A4372q and firmware is available for the iPhone 5 (Model A1428), iPhone 5 (Model A1429), iPhone 4S, iPhone 4 (GSM Rev A), iPhone 4 (GSM), iPhone 4 (CDMA), iPod touch (5th generation).
Developers can download the beta from here. Everybody else can download using the following links:
UPDATE: Apple released iOS 6.1.3, so you can NOT restore to earlier firmware (both original and custom), unless you have saved your SHSH keys. If you are on iOS 6.0-6.1.2 you can use evasi0n to jailbreak.
Using this tutorial you will be able to create a custom firmware, untether jailbreak and unlock iOS 6.1.2 running on iPhone 4. This tutorial uses Sn0wBreeze 2.9.11 for Windows.
Sn0wBreeze 2.9.11 allows users to preserve modem version for unlock.
iH8Sn0w released Sn0wBreeze 2.9.10 that brings support for untethered jailbreak of iOS 6.1.2. New version supports iPhone 3GS, iPhone 4 and iPod Touch 4G. It does not work with A5/A6 devices, like iPad 2, iPad 3, iPhone 4S, iPhone 5, etc.
Sn0wbreeze can be used to create a custom firmware with jailbreak and preserve iPhone modem (baseband) version for unlock. It can also be used to upgrade iPhone 3GS modem version to 06.15.
You can find the release notes below. You can download the latest version of Sn0wBreeze from here.
UPDATE: Apple released iOS 6.0.1, so you can NOT restore to earlier firmware (both original and custom), unless you have saved your SHSH keys. If you are on iOS 6.0 right now you can use this tutorial.
This is step-by-step instructions on how to perform tethered jailbreak of youriPhone 4 on iOS 6 firmware using RedSn0w 0.9.15 for Windows.
Tethered jailbreak means that each time you restart your device you will need to connect it to a computer and run redsn0w.
According to antenna expert and owner of website AntennaSys Spencer Webb, the iPhone 5’s increase in height and other changes in its design should improve signal reception. He wrote extensively about the antenna issues in the original iPhone 4.
Apple did not mention that iPhone 5 would use the recently approved (and Apple-designed) nano-SIM standard. Apple is relying on that even tinier subscriber module for GSM, HSPA and LTE networks. Unfortunately it is not possible to create nano-SIM out of micro-SIM. Cutting does not help, they are just not compartible.