Saurik through a new message in his official Twitter channel,
inform all about the return to the 'Home Page' of Cydia
ability to save your own certificate ECID even in firmware
In the past, we provided several guides in order to save
the ECID of your iPhone, or that certificate that will allow
to install a custom firmware even if Apple will change
the process of checking the authenticity of the software. All this
is much easier thanks to Cydia, which can save
automatically, by clicking on a button, storing,
subsequently, the server Saurik.
Specify, however, that the ECID saved now (speaking
holders of firmware 3.1) will not allow you to run anyway
downgrade the new firmware to a previous one, but could still
useful for the foreseeable future.
All iPhone owners 3GS, therefore, must perform this
procedure (when it becomes available for such Jailbreak
device) to make sure you can run the Jailbreak
with any firmware released by Apple itself.
-- Post From My iPhone3g