Windows Phone 8.1 being tested, according to AdDuplex data
the new Blue version of Windows Phone featuring IE11, it also could be the minor GDR2 update that also is expected. Back in March, we brought to your attention a job posting for Microsoft seeking a test engineer for Windows Phone 9 which is a separate project than Windows Phone Blue. The latter is more about merging different variants of Windows. Last month, speculation had Windows Phone 9 launching in October.
source: @ailon via WMPoweruser