Both MIGHTY AVENGERS #16 and NEW AVENGERS #43 are also crossing over with the SECRET INVASION series.
In Mighty Avengers we have a flashback several months that shows how Elektra came to be captured by the Skrulls and replaced by one of their agents. Brian Michael Bendis writes this issue and is aided by the art of Khoi Pham with does a lot of nicely drawn silent, action panels that demonstrate just how formidable Elektra can be and why she was chosen by the Skrulls.
Over in New Avengers we get to see the Captain America who escaped from the crashed Skrull ship going up against some of the other heroes in the Savage Land. I don't want to give anything away, but Bendis again provides a lot of background and some incite into the Skrulls. Here he is aided by artist Billy Tan, who does a nice job with all the characters, both on the Skrull world and in the jungle scenes.
By the way, when did Shanna become so blood-thirsty? Wow!