Hi, hey that's kind of old question
I'll try to answer as I'm not really a specialist.
It's called "GLOW", to me a "new school" effect. It can be done with several methods, one example:
copy the whole screen then past it with a % of transparency and of course it must be stretched (with a gradient too)
edit, note that in fact it's not always the whole screen (works if the object is centered) because it's getting to be called "radial blur" too ;P