You need to put the absolute float in a container to control the position.
float "twitter-container" left with a width
float twitter-feed absolute
twitter-feed will be absolute positioned to it's container which is "twitter-container"
The actual display of your <div> will very depending on whether or not it's parent container (<div>) also has a declared position.
That is, if it's parent container DOES NOT also have a declared position, the child <div> will do 1 of 2 things.
If position:relative, it will position as desired but space will be left as though that element was still in the natural flow. So you may move the 500 X 100 element down and over, but a 500 X 100 space will be left, as though it was still there.
If position:absolute, child is positioned relative to browser window and that position does not change even if window contracts or expands.
So be sure to give a declared position to both the parent and the child <div>.
Put your absolutely positioned div inside a relatively positioned div wrapper.