AMD's latest Radeon HD 6000 series graphics cards are slated to launch this month. The first two cards are widely expected to use the new Barts GPU but the confusing thing is that this isn't their high-end part. Instead, they are widely believed to be "mainstream" options and if benchmarks are to be believed, will perform somewhere around the Radeon HD 5850 mark.
EXPreview - AMD Radeon HD 6870 is based on Barts XT GPU, features 960 stream processors, 1GB GDDR5 memory, 256-bit memory interface, and memory clock of 4200MHz. It scored P16270/X7538 with 3DMark Vantage, and 19480 with 3DMark06.
Built with Barts Pro GPU, the Radeon HD 6850 comes with 800 stream processor, 1GB GDDR5 memory, 256-bit memory interface, and core/memory clocks of 775/4000MHz. The card scored P14872/X6549 with 3DMark Vantage, and 18750 with 3DMark06.
The site has also a comprehensive list of other competitive cards like the Radeon HD 5870 and HD 5850 for comparison. Click here to see the full list.