As Lion now supports Resume, does it mean most softwares no long needs starting at login?

Question

As Lion now supports Resume, does it mean that most software no long need starting at login, as when they are open, they remain open in the next boot-up?
Of course it won't apply to those tools which only run once at login and auto quit afterwards.

Answer 1

Resume is an option that is enabled by the user; if the user doesn't select the checkbox when he shut-down Lion, then the applications will not be re-opened at start-up.
Resume is an option for applications that don't run in background, such as text editors, documents editors, browsers, which are opened when necessary. If also background applications would rely on that, then users would not have any possibility, if not closing all the applications they don't want re-opened by Lion; differently to have a background application re-opened when the Lion is shut-down or restarted, they would also have the other applications re-opened.

Answer 2

Resume is a feature designed on a simple premise: Give the illusion of coming back to your computer like nothing ever happened. Under the hood, there's actually not a lot of magic going on.

What OS X does, is take a "snapshot" of the apps you have open—consisting of small details, like window dimension and position, etc. (you can see the data it collects by looking in ~/Library/Saved Application State/). When the system reboots, and OS X is loaded once again, the system retrieves this information and then launches the app for you. Since it takes time to actually load apps, the information it gathered before is applied, giving the illusion as if everything is already loaded and ready to go. This gives the system time to actually get things up and running, while the user is none the wiser.

The feature was ported over from iOS (among other's that have found their way in Lion), which does essentially the same thing (even going as far as taking a screenshot of the running app to cut down on the appearance of loading).

So does this mean you'll never have to launch another app? That depends entirely on you and how you use your Mac. But it does make a reboot less of a chore for those that like to multi-task, or always have a handful of applications running and organized in a certain way. It also makes the experience less "jarring" as things come back pretty much exactly how you left them.

This feature is applied to all the user-based applications (things like Mail and Safari), while system level components (kernel_task and mdworker) are exempt because quite frankly, all that matters to the user is the stuff they run. The operating system's fundamental components always do their own thing, outside of the user's control, and a user shouldn't (and doesn't) need to worry about them.

If you care to learn more about all the new features in Lion, you can read the fine article over at Ars Technica. It is truly exceptionally written and one of the finest pieces you're going to find on this new cat.