To some extent I agree with Great Mambo Chicken.Dip 1 will be the vanilla version. The red/blue glasses version will be in dip 2. Dip 3 will be the extended edition with documentaries.
They know 2010 will be the year they will make a good profit on this Avatar property so putting one version (bare bones) out in May and one in November/December is the way to go.
The eventual Avatar Blu-ray 3-D version will use HDMI ver. 1.4 spec to deliver 3-D content to the new HD televisions. State of the Art technology to help sell 3-D HDTVs.
Look at it like the Lord of the Rings DVDs with the multiple versions.