This year Smith & Wesson have launched the M&P15 PS and PSX piston operated AR-15 rifles.

M&P15 PSX
The only difference between the PSX and PS is that the PSX features a Troy 7″ modular quad rail handguard.

M&P15 PS model and Piston Operating System
Photo ⓒ Remigiusz Wilk (REMOV). Used with permission.
Specs:
Barrel Length: 16″
Barrel Twist: 1 in 9″
Overall Length: 35″ Extended/32″ Collapsed
Stock: Collapsible 6-position
Weight: 6.5 lbs.
Finish: Hard Coat Black Anodized
I do not know the MSRP on either model.
In February S&W will launch two new M&P15 (AR-15) models. The M&P15 MOE (Magpul Original Equipment) features, as the name suggests, as many Magpul accessories as they could fit on the rifle.

Click to expand.
Specs:
Model: M&P15 MOE
Barrel Length: 16”
Barrel Twist: 1 in 9”
Front Sight: M4 – A2Post
Rear Sight: Folding Magpul MBUS)
Overall Length: 35 ”Extended / 32” Collapsed
Stock: Magpul MOE
Weight: 6.5 lbs.
Finish: Hard Coat Black Anodized
Other Features: Magpul MOE Grip, Magpul Handguard, Magpul PMAG
Two colors will be available: Black and Flat Dark Earth (what the cool kids call tan these days).
Overall I think this is a compelling package. Instead of buying and AR-15, only to spend more on Magpul accessories you can just get an M&P15 MOE.
No word on pricing.