The more I dig through Geoff Johns' run on Green Lantern readying a summary of the generalities (a post I'd thought I'd get around to five days ago), the more I end up latching onto specifics.
Swollengoat on the DC Message Boards called my attention to the unnamed figure sitting behind the gremlins in GL #43. As others have noted already, the word "starlings" (not likely to be the bird) plus the shape of his mask is a giveaway that it's Evil Star, a villain who hasn't otherwise been seen in recent continuity. Edit: Evil Star is mentioned in Green Lantern: Rebirth #1. Guy Gardner makes a disparaging remark about his worthiness as a villain. John Stewart does not disagree with that comment. To stay true to Johns' methodology, Evil Star will probably be the subject of some retcons.
So, two topics: Is he going to figure huge into Blackest Night? What's up with him, generally? Given that the Kroloteans (gremlins) are looking inside Black Hand and according to William Hand, they don't find what they're looking for, it seems very unlikely that he is the Big Bad. Scar tells us that the Big Bad will rise as events move on. Evil Star is obviously already "up" and doesn't need to rise. It seems like contact with the Big Bad is what they were looking for. Evil Star is also mentioned in #42 by Blue Lantern Sister Sercy as an oppressor of her people.
When the Kroloteans first surface (GL #4) Hector Hammond tells us that they took apart "planes in the war". This, combined with the label "gremlin" and their damage to Cowgirl's plane is very interesting. Because "gremlin" was a term that pilots actually used to label unknown causes of damage to planes. As though little mischievous beings were responsible.
Why do I think this is interesting? Was there an important event in Hal Jordan's life that pertained to mysterious damage to an airplane?
Green Lantern #29:
Martin Jordan: "I'm having some problems up here, Ferris. Oil's gettin' eaten up quick. I think the last of my torque pins just failed. I thought this was sent to I-level for repair."
Carl Ferris: "It was."
Looking down the road, I think we're going to be surprised in a future story to learn that Evil Star is basically the murderer of Martin Jordan. That's bound to set Hal off. Atrocitus has prophesied (in GL #37) that Hal will go renegade again... maybe when he finds out about this?