How about: have a really cheesy wallpapers in the pre-release builds which conveys the message (perhaps with explicit text right in the wallpaper image) that this is not a released build. Also, how about making not-released builds simply expire. The build should know that nobody ought to run it past a certain date. (If such operation is needed internally, it can be rigged with an extension mechanism built into the expiry.)
Isn't that the thought behind the watermarks they've had since Win7-ish? I remember messing with beta builds and reading about people using them (again, to avoid paying for it for a bit as mentioned in another comment) and jumping through all sorts of hoops to disable or hide the watermark - aside from buying a license of course.
There's probably a point at which any more effort put into carrots (new features or wallpapers on official builds) and sticks (nag screens, watermarks, expirations, etc on old builds) just becomes more trouble than it's worth.
I like trying out leaked builds of programs or OSes as much as the next bored nerd but I can't imagine ever running something as primary OS on any machine I count on for anything. That stuff is for old computers that aren't being used or VMs.
Expiration has an additional positive effect in that it prevents use of the buggy builds and is also relatively easy to implement, especially when the prerelease build can phone home.
Developer builds do expire. Dealing with that with one of my customers. A slick little IT guy decided that he would put his developer copy of Windows on this particular non-profit's computer to save them money. All of a sudden 3 weeks ago they get a message about their OS being expired and it wouldn't boot up without a windows boot disc.
If I'm not negatively affected in any way, why should I upgrade?
Also, how does a user who doesn't upgrade notice a change in wallpaper which doesn't take place until after the upgrade? By looking at someone else's desktop which is running the release version?
What if the user has changed to a custom wallpaper, and doesn't remember what the original wallpaper of the leaked OS looks like?
>Also, how does a user who doesn't upgrade notice a change in wallpaper which doesn't take place until after the upgrade? By looking at someone else's desktop which is running the release version?
The type of person who is downloading leaked pre-release builds in order to have the latest and greatest generally follows the latest news about new leaked builds.
Rather than a hard cutoff, you could have the colours of everything on-screen desaturate as time passes beyond the expiry date, eventually ending up entirely monochromatic.
I think that would get the message across quite effectively :)
"Super secret preview version of Windows X leaked! Download here!"
(...3 weeks later...)
"People trying Super secret preview version of Windows X get their hard drives wiped out! Was this Microsoft's plan all along? Please tell what you think!"
