WhatsApp is apparently running a closed beta for its Windows Phone app -- there's no way to sign up for it, but it is being tested by a limited number of users. According to a new report, WhatsApp Beta picked up an update, introducing several new features and improvements to the app.
The folks at WPCentral report that WhatsApp Beta comes with several speed improvements, which boosts the overall performance of the app. The latest update also gives users the ability to view the number of participants in a specific group, as well as some UI changes for the picture preview window and the option to add captions to the images you share.
The features are not yet available in the stable version, but they should come at some point in the near future. We'll update you as soon as WhatsApp for Windows Phone picks up this update.