I really don't think that it's practicly possible for the film to be ready at the summer of 2006.
I mean,it's not a low-budget movie we're talking about here,but an Indiana Jones film!
They haven't even finished the casting yet,and the script is in a very first draft.
To be honest with you,I really don't think that this movie will be made.And it shouldn't as well.I am a very,very,very big fan of Indy,I have his movies,books,comics,but I just know when enouph is enouph.
A positive thing with Indy is that the audience loves him not so much from the action he delivers,but for the character himself.This means,that even if they made an Indy #4 with a 60-year old Harrison Ford,the audience would propably still like the film.But come on guys,Indy at his 60?!
It's like...I dunno...watching a Matrix movie and seeing no sunglasses in it...