in the blog of this guy http://pablo.lizardo.info/?p=220 i saw this screen shot http://pablo.lizardo.info/wp-content/uploads/nodos.jpg , but i cant find miself the fade node.
where is it? thanx.
giorgio martini,
That is a texture node - it takes the name of the texture. It looks as if he has created a blend texture and is using it as an input in the compositor.
hello, i want to answer and i need to put some images so i chose for write a post for give you the solution. it´s in spanish but i thinks that you can understand it anyway… the link to the post is: http://pablo.lizardo.info/?p=234
basicly i create a radial texture (Blend texture with sphere type). Then i add it into the node editor. and i use for two proposes. One: for masking the blur filter , and TWO: for add dark border with the mask too.
well… i dont speak english well. sory! hope you can understand and solve your problem! 
saludos!
to fade something over time, use the set alpha node fed by a time node to the Fac input, but switch the time node curve to go from 1 to 0. Alpha-over that ontop of the background.