The first and I hope not last monitor with that panel is ASUS PG258Q.
It's not same overclocked panel like we have on all 24" 144Hz TN monitor and that's good.

press release

ROG Swift PG258Q gaming monitor
ROG Swift PG258Q is a 24.5-inch gaming monitor that features a Full HD (1920 x 1080) panel with a native 240Hz refresh rate. Swift PG258Q has a 1ms gray-to-gray (GTG) response time and built-in NVIDIA® G-SYNC™ technology to eliminate lag and frame rate stutter for the smoothest, fastest, and most breathtaking gaming visuals imaginable. Its narrow bezel design makes it perfect for expansive multi-display setups.
Swift PG258Q has a revolutionary design finished in ROG's new Armor Titanium and Plasma Copper color scheme, and has built-in ROG light effects on its stand to add ambience to gaming set-ups. In addition, Swift PG258Q features ASUS GamePlus in-game enhancements and ASUS GameVisual technology for optimized gaming visuals.

Also ASUS announced 24" 180Hz TN monitor - ASUS PG248Q. Looks like it's based on same panel just like any current 24" 144Hz monitor.