Thanks to Julio for translating the announcement on the official Chivas site:

"Its official, Carlos Vela – under-17 World Cup winner and the highest goal scorer in Peru 2005 – has signed for Arsenal. This is what Néstor de la Torre, Vice-President of Futbol del Club Deportivo Guadalajara, said. 'We made three changes to the contract, which were accepted by the people from Arsenal. I asked what projects they had for Carlos and they said that they were planning on loaning him out to a club so that he could gain experience before joining the Premier League, but Arsenal is now responsible for this.'"

"Arsenal have signed him for 5 years and it will be his father, Mr Enrique Vela, who will sign his contract, which includes a clause that states that if Arsenal decide to sell him, Chivas will have a worldwide first option on him. With this Carlos Vela will realise one of his dreams while the Rojiblanca [Chivas] sell this youngster to one of the biggest clubs in the world."

Fans FC have more quotes from de la Torre, suggesting that the choice of loan club or even country is not yet decided. "They have various countries as an option. They will find a team where Vela will continue his development in order to then integrate himself in the Premier League." On the one hand, this makes sense, Valencia still seems an unusually big club to be getting involved in this. But on the other hand, it really doesn't fit with the FIFA regs. How could his family be claiming to move for reasons unconnected with football, if the very country they move to is decided by Arsenal's search for an appropriate and willing loan club? Anyway, Vela's dad says they're moving to Spain...

Good news for the future, we hope. But there's still a long way to go till we see him play for Arsenal. If he does, he could become only the second Mexican to play in the Premiership (following Jared Borgetti at Bolton Wanderers).