You can't fight openly in the military in the US, but the UK is requesting specifically gays to guard the queen.
http://www.dailystar.co.uk/news/view/99869/Fury-over-PC-job-ad-for-elite-force-/
http://www.dailystar.co.uk/news/view/99869/Fury-over-PC-job-ad-for-elite-force-/