As you can see the site was just redesigned, i wanted to make this update along with version 4.1, however since beta testing takes more time than i originally expected i went ahead with the redesign and published it earlier.
For all WPJB users this means slightly updated client panel, most probably some new features will be coming there soon and since the changes on site also included internal engine the updates API should work faster although i doubt you will notice any difference as the speed improvements are in milliseconds.
As for version 4.1 as i am guessing this is something you are interested most, i do not have an exact release date as it is hard to tell right now if Quality Assurance will find some issues or not, if you cannot wait to get it is best to subscribe to this blog or Facebook fanpage, as soon as new WPJB will be released there will be announcement on both sites (and via automatic updates if you are using version 4.0.3 or newer).