An important court decision snuck by nearly unnoticed this week when a judge gave spyware companies the green light to plaster your PC with pop-up ads.

U.S. District Judge Gerald Bruce Lee said it was OK for the ad company WhenU to serve whatever pop-ads it wanted on U-Haul's (NASDAQ:UHAEQ) website -- even those of a competitor.

WhenU is similar to the better-known and more-reviled Gator. These companies install programs on your computer that monitor your surfing habits and display pop-up advertising when you visit certain sites.

You could theoretically see ads for AOL Time Warner (NYSE:AOL) on a Microsoft (NASDAQ:MSFT) website, for example. Looking at Ford's (NYSE:F) new car designs? WhenU could cover the pictures with General Motors (NYSE:GM) vehicles.

Problem is, most users with such "spyware" on their PC have no idea it's there; it's usually snuck onto their hard drives after they've downloaded another program such as a file-swapping application or a game. Thus, the judge's rationale for the decision is startling: "Ultimately, it is the computer user who controls the windows displayed on the computer desktop," he said, as if users actually choose to see more pop-up advertising!

If everyone who had spyware on their computer actually knew about it, he'd be right. But they don't, and he isn't. Let's face it, even people who know about Gator and actively work to keep it off their PCs (through free programs such as Lavasoft's Ad-aware) have a hard time doing so. It's a vile, invasive program that takes away a user's ability to control his Web-surfing experience -- exactly the opposite of what Judge Lee thinks.

What are your thoughts on spyware? Please join us on the Webmaster's Corner discussion board and have your say!