When I first ran the Black Talon flashpoint, there was a 50 in the group and I got xp. So, yes, people will get xp.
Ya like 25 xp per mob or so. Friend ran a lvl 11 toon of me through esselse and I get 2 xp per mob.
This was yesterday.
And it should work like this, would be WAY to easy to power lvl toons else.