Ok, before we get any kind of confirmation from 20th Century FOX themselves stating that filming for this sequel has begun, take this with a very small grain of salt. Anyways reports from various Mexican Dragon Ball blogs are suggesting that filming either has begun or is about to begin for Dragonball Reborn. Here is that report.
From 01.06 on Tuesday began filming in the city of Durango, Mexico, filming for the next movie Dragon Ball, DB reborn which would be the continuation of Dragon Ball Evolution. This has caused cuts in the streets and remodeling in several places in the town. Many viewers have come to watch the recordings. This film is dated mid-2011.
Well will update everyone once we receive any kind of information ourselves on this.