Microsoft Build 2014 is taking place in San Francisco today through Friday. Registration has long been sold out for developers prepared to pay the $2,095 fee.

As soon as Joe Belfiore came on stage, he announced that Build 2014's keynote would be about Windows 8.1 Update 1 and Windows Phone 8.1.

So no big details were announced on Windows 8.2 or Windows 9 (though there was a little tease for a future version of Windows as we'll tell you shortly).

Windows 8.1 Update 1 is the leakiest update to Windows yet after a Microsoft goof let it out of the bag early.

Windows 8.1 Update 1
Out on the town already: Windows 8.1 Update 1

The new update features improvements to the Start Screen including the ability to boot straight into the Desktop, the return of shutdown on Start and a more familiar taskbar to unify the old and new user interfaces. It's 700MB in total and almost all the updates acquiesce to disillusioned desktop users.

You're now able to access the taskbar from any screen and pin Windows Store apps to the taskbar alongside desktop apps and favorite websites.

Terry Myerson
Operating systems head Terry Myerson

Microsoft says that "navigating with the mouse and keyboard will feel more familiar and intuitive because there's more consistency with where controls are and how they work".

The company also promised that partners can more easily build lower-cost machines — such as devices with 1GB of RAM and a 16GB hard disk drive - by a change in the way Microsoft licenses Windows.

8.1 Update 1
Windows 8.1 Update 1 is unveiled

The Windows 8.1 Update 1 release date is April 8.Current Windows 8.1 customers will receive the Windows 8.1 Update for free through Windows Update, while Windows 8 customers will receive the update free through the Windows Store.

Microsoft also gave us a tease - the return of the much-wanted Windows Start Menu in a future update to Windows 8. Expect that for Windows 8.2 then. Here is the tease. As you can see, it also shows Metro-style apps floating on the Desktop - launched apps will appear in the Start Menu.

Tease
It is back!

"I think there's going to be a lot of happy people out there," said Microsoft's operating systems group head Terry Myerson.

"We are going all in with this desktop experience to make sure your applications can be accessed and loved by people that love the Windows desktop,"

We think it looks great - but it's a crucial sign of just how far Windows 8's stock fell by attempting to change the UI we all know. All these OS changes are a clear reaction to user demand, but it could well be a little late for Windows 8.

Windows Phone 8.1 and Cortana

In terms of phones, Build 2014 should answer some intriguing questions after recent acquisition of Nokia (and its new-found devotion to Android). Windows Phone 8.1 has been demonstrated at the show's opening keynote, while there was also the advent of Cortana, Microsoft's Siri-like voice assistant. Predictably, Cortana is powered by Bing.

Cortana being shown off on stage at Build 2014
Cortana being shown off on stage at Build 2014

Further personalization is a main aim with the Windows Phone 8.1 update - there's an enhanced Start Screen that allows you to customise with your favourite picture, Action Center, which shows new activities and notifications at a glance; and Senses.

Senses is designed to "take the work out of managing data use, storage space and battery life".

Action Center is one of the most appealing features
Action Center is one of the most appealing features

Windows Phone 8.1 will start rolling out over the coming months. It will also come pre-installed on new phones starting this month.

Microsoft says that "Cortana will launch shortly in the U.S. as a beta, in the U.K. and China in late 2014, and in other countries in 2015".

New Nokias

Nokia announced three new Lumia smartphones for Windows Phone 8.1, including the flagship Lumia 930, cheaper-though-still-4G Lumia 635 and the first dual-SIM Lumia - the 630, which also comes in a single SIM version, too. Read more on the Lumia 630 and Lumia 635.

Both the 630 and 635 feature 4.5-inch LCD displays, 1830mAh batteries, and 1.2GHz quad-core Snapdragon 400 processors.

The 930 has a 5-inch, 441 ppi Full HD display and a 20MP PureView camera. It runs on a 2.2GHz quad-coare Snapdragon 800 processor, has 32GB of internal storage and 2GB of RAM.

The new Lumia 630 and 635
The new Lumia 630 and 635

Microsoft's Stephen Elop talked up dual-SIM phones, adding that analysts predict over 100 million will be sold in 2016.

There was also some buzz around a mythical Windows Phone 8.5 before the event, a as-yet-unannounced version of Windows Phone seen in an emulator.

Common platform

Microsoft also announced a change in the way apps are coded - a converged developer platform developers code for both Windows Phone 8.1 and Windows 8.1 Update.

Microsoft has talked about this becoming the case for some time, but evelopers can now use approximately 90 percent of the same code, a single packaging system, and a common user interface to target apps for phones, tablets and PCs.

A mini Surface?

There have also been rumours that a new Surface Mini or Surface 3 may pop up at the conference.

TechRadar previously reported that the launch of a Surface Mini may have been held up because Microsoft had to draft in developers to help with the Xbox One.