*SPOILER ALERT TO THOSE WHO HAVEN'T READ THE SERIES!*
I don't know where you heard that, maybe it's common knowledge, I'm not denying it. But that's exactly where I THOUGHT the first movie should end. But the ending should incorporate their capture and the showdown at Malfoy manor.. that would make an exciting ending sequence..
And not only that, but I think it should carry on to Dobby's death. Because in the book, that was when Voldemort acquires the Elder Wand from Dumbledore's tomb, Harry has the vision by Dobby's grave if I'm not mistaken.
It will close the movie perfectly for a few reasons:
1) Voldemort has the new wand, so it is almost a new story for him
2) Dobby is dead, and that's when Harry comes to the realization that he has to abandon his hope and search for the Deathly Hallows, and has to continue pursuing the Horcruxes.. So it's almost a new story for Harry..
And then the 2nd movie should open up with the break in at Gringotts.. that would make an exciting opener!
That's what I would do.
AHH! So excited!