The first thing I noticed after I updated my Galaxy S2 to ICS (Ice Cream Sandwich), was that the same button press combo for taking a screen shot wasn't doing the trick anymore.
Luckily, a quick Google search taught me how to do it.
On Gingerbread, the shortcut was to hold the Home button (bottom middle of the phone) and then quickly hit the power button, but now, in ICS they've changed it to be Volume Down + Home button + Power button, and you must press them at the same time. EDIT: ahh correction, just Volume Down + Power Button (stupid guy on youtube!)
I always wonder why developers would change stuff like that? I mean, the windows button on a keyboard still opens up the start menu, no matter if it's Windows 95 or Windows 7.
Anyway, glad that's sorted, will keep you guys posted on the rest of my findings!