There seems to be a lot of Alien Invasion films coming in the next few months, Recently Sam Raimi has been linked with directing the film "EDF" or earth defence force, there is SKyline, trailer below and Battle: Los Angeles, sorry coudn't find a good trailer. There is also Cowboys and Aliens which i will let you make your own mind up about

Anyway here are 2 trailers, first Skyline then Cowboys and aliens, Enjoy

Skyline
Cowboys and Aliens

By Steve Jarvis