Cebit 2010 talk about E-government, Free Software and Cloud Computing are mentioned everywhere in different context... but why don't we put them all together? The cocktail you can get will look really impressive. Let's see how they fit together: How open source and open standards are the perfect and the only sustainable way to implement e-government solutions, how the Cloud approach gets a lot of sense applied to e-government and is sometimes the only cost-effective option available for some sectors, how Cloud Open Source technologies give us the flexibility to implement all our needs and how Cloud Computing is fully compatible with e-government technological needs. Now let's put all together and what do we get? The perfect mix. One implementation, developed by Andago, is our solution "Open Cities as a Service": an open source interoperability and e-government platform based in cloud computing.