Apple today released iOS 7.1 beta 4 to developers. The latest beta version of iOS 7.1 carries build no. 11D5134c, and is available for 31 devices. Developers who prefer a clean install can download this build from the iOS Dev Center.
The beta 4 release notes mention iMessage, Safari, and UIKit fixes. The previous three betas brought several interface enhancements, and the present release comes hot on the heels of a rumour claiming iOS 7.1 beta 4 would be pushed out tomorrow.
Stay tuned, and refresh for updates.