pod2g has just updated his blog concerning the A5 jailbreak. Here’s what he said:

The exploit I used to inject the untethering files to the 4S relies on having a developer account, and can’t be released publicly.

It’s the same reason why @MuscleNerd has an iPad 2 tethered jailbreak but couldn’t distribute it.

So, we need to find a distributable exploit to remount the system partition read/write and to set Corona files at the correct places.

Why A4 version of Corona was easier to release ?

Because a tethered jailbreak is a good way to install Corona!

Why don’t you do a tethered jailbreak then ?

A tethered jailbreak also relies on an exploitable vulnerability that we still haven’t found yet !