Cast when stunned also works on block recovery?

Basically, a block recovery is a stun. When the attack that you blocked wouldn't have been blocked, it would have stunned you, therefore you go in block recovery. If the attack wouldn't have stunned you and you block it, there is no block recovery.

Short in short, block recovery is the same as being stunned, with the only exception that the many faster block recovery sources make it very easy to shorten this duration to almost nothing, making it much less annoying then being stunned.

So as block recovery is a form of being stunned, will it also trigger the stun trigger-gem? It would make it a very powerfull gem for block builds, whereas if it doesn't I don't really see the use of it.

Can someone enlighten me? Who is using cast when stunned and how do you feel about it?

Yes and I feel positive about this.

Can anyone else confirm this?

Scroll down to the cactuar on this page: http://www.pathofexile.com/forum/view-thread/608759/page/4

Pneuma claims to have built around precisely this (having 75% block chance and using Cast when Stunned), and I trust pneuma, so I would say yes.