EVE Online : All About Incursions
"The Sansha's Nation is seriously pissed and doesn't care about politics; trust us, you would be quite mad as well if you were stuck living with giant spikes on your head 'n' shoulders." So starts the latest blog at the EVE Online site from CCP Ytterbium. In the blog, details about precisely what incursions are and how players are affected by them are detailed. Incursions are detailed from system wide effects to how to counter the Sansha.
Participation in incursions grants rewards, of course. Completing sites will secure ISK and CONCORD loyalty points, the latter actually paid out only when an incursion has been successfully repelled by the destruction of its final boss (thus making it particularly important). CONCORD only pays for a job that's finished, private.
Please also note that, - besides the fact that attempting to solo an incursion is a very, very bad idea - the rewards themselves are designed for groups and based on site objectives. The NPCs themselves have no bounty, no loot, and very little salvage as we wanted players to focus on the actual encounters.