This month marks the final demise of AutoPlay on Windows XP. AutoPlay has always been turned off by default in Windows 7, but for compatibility reasons Microsoft had hesitated to reach back into the past and make the change for Vista and XP. On this month's Patch Tuesday, Microsoft took the plunge and disabled it. It's still possible to re-enable it for all versions of Windows, of course, but any time Microsoft turns off a feature you should take it as a strong suggestion to keep it turned off.
The late 1990s marked a time that Microsoft turned into the Age of Auto Everything. It was based on a decent and reasonable-sounding idea: The computer should try to anticipate your needs rather than wait for you to tell the computer what to do. The Age of Auto Everything started rather innocently and unobtrusively, with features like AutoCorrect in Office 95. Those little red squiggles under words pointed out possible spelling problems without you having to do an explicit spell check, but didn't get in your way or pop up annoying dialogs.
Other Office Autos didn't sit that well with me, like AutoFormat -- which tried to convert things like a row of dashes into a solid line, or a line starting with an asterisk into a bulleted list. The AutoCorrect feature also did its share of damage by converting two consecutive dashes into an em-dash, or regular quotation marks into typographical "smart quotes", which often don't render correctly when displayed, for example, on a Web page. It's not all bad though; AutoCorrect fixes common typos like "teh" to "the" as well.
Despite Microsoft's best intentions, the anticipatory goodness of the AutoCorrect and AutoFormat is often outweighed by the annoyance when it guesses the wrong way. For the past 15 years I've learned how to turn off or tone down these features as I've migrated through all the versions of Office. The penalty for forgetting to do that is an email from an annoyed editor saying, "Turn off smart quotes!" It doesn't help that the settings are buried deep within the menus in complex dialogs, which means that users often just live with (and swear at) the defaults.
Windows AutoPlay went beyond annoyance, though, and became a threat. It comes in two flavors. The basic AutoRun functionality allows any removable media with an AutoRun.inf file in the root directory to start a program immediately without any user interaction. Back in the Windows 95 days, this was convenient for product setup CDs, since there was no need for users to know anything more than how to drop the CD into their drive. (Remember, it was the golden age of the AOL dialup user; even dropping a CD into a drive was pretty technical.)
The other flavor of AutoPlay is more subtle than AutoRun. Windows will scan the content of the removable media and try to offer a set of options that make sense for the type of files it finds. So if you insert a USB flash drive full of MP3 files, Windows will offer to let you play them using whatever music players are registered for AutoPlay. It's not exactly unobtrusive, though, because it always pops up a dialog asking you what you want to do with the files unless you select "Always do this" in the dialog for each different content type.