Your Lumia smartphone is going to need 8GB of internal memory and the Lumia Denim upgrade (Windows Phone 8.10.14219.341 or above) to be able to make the jump, according to a company FAQ.
That ties in with previous rumours coming out of Redmond: Microsoft had already promised to roll out Windows 10 Mobile by the end of 2015, and it looks like it's going to hit its target with not much room to spare.
10 is the magic number
So what extra goodies are you going to get on your Lumia handset when the update finally shows up? Like the forthcoming Xbox One update, Windows 10 Mobile is essentially the full Windows 10 with a few tweaks.
That means universal apps (like Word and PowerPoint) are going to run in a similar way as they would on the desktop, albeit shrunk down for a smaller screen. Live tiles are still present and correct, and as you would expect, Cortana has a big role to play in the brand new Windows 10 Mobile as well.
As yet we don't know specific details about release dates for particular regions or particular Lumia models, but we'll keep you posted as we learn more in the weeks ahead.