How is packageinfo.firstinstalltime set?

I get that it's likely automatically set when downloading and installing from the marketplace; however, what about preloaded applications? How does the device manufacturer set this value or do they set it at all?

I've noticed that with Froyo, preloaded applications behave poorly with regard to the market and updates. When the marketplace is updated, the preloaded apps don't know and there's no notifications. However, I've heard this was fixed with Gingerbread as long as apps are 开发者_如何学Pythonpreloaded properly. The only change I find in the API related to this is with packageinfo.firstinstalltime. So, how does the device manufacturer set this so that android can properly notify users of updates to preloaded apps?