EDIT: seeing the reviews here saying thats its helpful is there any chance of it getting stickied?
Because iv just been asked how to do it and its one of the easiest things to do...
and i wanted to make a tut
everyone dont hate me u can lock or even remove it later if you dont like it

open the render

duplicate it

have 4 copies and the original so 5 in total

dont TOUCH origial ATM leave it where it is, open the motion bluring window

click the preview button if u haven't already, and select the angle u want the render to blur towards. repeat for ALL COPIES (personally i use 0, 90, 45, and -45) STILL DONT TOUCH ORIGINAL

now move original to top u will see a slight glow around it

all i did here was add a black background so u can see what has happened after motion bluring

to tidy up merge the COPYIES together nerver merge the original with them (if u need to move them link them together)

now adjust the transarency to how you like (in this one i have taken it down to 50%)

and now you should have used motion blur to create a nice method of bluring that is able to be used other then smudging
Edited once, 26/2/10 - 5:45pm.
Posted on Friday, 26th February 2010