So, the style this year is digital grey patterns.
Just kidding. Contractor fashion is a realm in and of itself, but civilian, so there are some personal touches which the soldiers here (obviously) can't reflect.
First - men's fashion hasn't really changed. Cargo pants or khakis and a polo shirt is the outfit of choice. Usually with brown combat boots or sometimes hiking boots (most seem to prefer the combat boot style to reflect their "authenticity"). Button up shirts are also acceptable, but much less common than the polo.
Women: although the khaki/polo combo can be seen, I have recently encountered a surge in khakis with a flannel button-up over a t-shirt of some sort. Originally I noticed this style predominantly on KBR employees, who form their own little subculture here on Victory Base, but recently the style has spread to the DOD contractors as well, so I have to assume it reflects some ethereal trend in the female subconscious here.
It is not surprising, of course, as we've had a few years of 80s fashion, so the resurgence of 90's fashion (read: grunge) is the next logical step. And everyone's already wearing the boots...
In looking up grunge, I found this awesome timeline for people who fell in the cracks between major music movements.