Ok, so i checked out http://android-developers.blogspot.com/2011/02/animation-in-honeycomb.html
He says you can animate the property of an object in a given time. A
I've created a small library ViewPropertyObjectAnimator that can do that in a very simple way (and uses a similar approach to this proposed by Tomer Weller).
You could achieve this animation with (assuming the mLinearLayout is the animated View and mEndWidth is the end value of the View's width):
ViewPropertyObjectAnimator.animate(mLinearLayout).width(mEndWidth).start();