Nokia is preparing to push out its Cyan update to its Lumia devices and for most phones, late summer will be the timeline that cover most of the devices the company has shipped. For those not familiar, Cyan is Nokia's Windows Phone 8.1 update and includes a few Nokia specific features.
It is important to note that the roadmap is for Benelux region. Considering that Nokia has generally done a good job of rolling out updates to most regions in a timely fashion, expect a similar roadmap for other countries too.
If you haven't done so already, check out our review of Windows Phone 8.1 to see what all the update will bring to your Lumia device. It's certainly a large update and brings many new features such as customizable live tiles and of course, Cortana.
Along with Windows Phone 8.1, there will be updates to the camera roll and Creative Studio and Nokia Storyteller.
This roadmap was not intended to be shown to the public so the information is subject to change. But, even if it does change, we can't foresee the dates slipping by months, likely weeks, if they change at all.