WMPoweruser noticed a job posting on Microsoft's website confirmed that the software giant is planning to release a new major release of Windows Phone by the end of the year:
Now a job posting by Microsoft for a Software Development Engineer in Test has confirmed that Microsoft is targeting the Holidays for the next major release, the usual pattern for the Windows Phone team.
The relevant excerpt says:
This is a great time to join as we’re completing our current release are getting ready for our next release targeting the holiday of this year and we’re chartered with keeping the momentum for Windows Phone by bringing new killer devices and delightful user experiences.
Again according to Mary Jo Foley we can expect two minor updates, the so-called GDR2 and GDR3 releases of Windows Phone to hit before this, likely providing some desperately needed bug fixes.