As all the big sites have been updating their style recently, I've noticed this effect on a few sites and I'm wondering how they do it.
Its like this normal gradient effect, with this pattern, abbit similar to a dissolving effect, but not quite that...
JSFIDDLE: Its on the top menu bar on this site: http://jsfiddle.net
Twitter: Again, its on the top black menu bar on http://twitter.com.
Youtube: Its like the whole of Youtube's background but its quite hard to notice on that one. http://youtube.com
Do you guys see what I'm talking about?
How would I get that effect in Photoshop?