Thanks to Dev team, it is now possible since this Sunday to spend completely in firmware 2.0 for users of‘IPhones V1.
The tutorial, explaining you the procedure to follow step by step, has been prepared by Gotcha here.
Despite everything, it is not yet clear enough, a tutorial on video, made by Hades, is at your disposal here.
I remind you that the solution PwnageTool 2.0 currently does not know how to unlock theiPhone 3G. The jailbreak is however available.
[Thanks Fxpicsou, Gotcha007 & Hades for the tutorials]