Just tried this feature with V7.1 and posted a topic and selected the global announcement check box.
I don't see it anywhere.
1) is there a setting in the control panel I missed?
2) is there some issue with the cache time?
3) where is it supposed to appear?

Never mind I guess it was a cache issue they finally appeared as a topic in all the forums

Here I was hoping to chime in and be the hero, but failed when it fixed itself :x...

I'm hoping that Global Announcements get some attention in the future, possibly show them on the category index at the top of the page for X amount of days...

All good idea's