there is nothing you can call "online community", there are only few ppl pop in and out on GPGnet to play some missions or disconnect soon. Very sad, because the game is great fun in mp.
But there is also a lack in support for this game -- no patch, no new maps, no balancing. Again very sad, because a game like that where you cannot collect items like in other A-RPGs (i call this one Top/Down-Shooter/A-RPG hybride game), needs new content/maps to keep ppl playing it.
Me and an online-friend played space siege online for some weeks (and formed a mini-fun-clan on GPGnet) and beat all difficulty modes and maps several time with different charakter builds .. so what is left after that? As i told above, no further support since month .. not the smallest statement about a patch/content-patch from GPG.