Dutch site WP7.nl has claimed that the long-awaited upgrade has become available via the Microsoft Zune syncing software.
"I just hung my Nokia Lumia 800 to Zune to justsome photos to sync and tadaaaa! There is an update ready!" the site reported (translated).
Not all users are detecting the update so it may be that Nokia is rolling out the new software to selected users or in certain territories initially.
It brings many of the same features, including customisable Live Tile sizes and the ability to set Google as the default search provider within the Internet Explorer app.
Users who were bold enough to 'flash' their handset were able to download and install the software on their Lumia handset