CNET: Can't stop the pop-ups
Pop-up blockers are losing the arms race, with pop-ups effectively blocking the blockers. As many as 30 percent of internet users currently use pop-up blockers, and Microsoft's upcoming Internet Explorer release is set to both include a blocker and have its default set to on. But, even as pop-up blockers become prevalent, new methods of spawning windows call their effectiveness into question.
Many of the pop-up blockers merely filter out the "openwin" command that opens up a daughter window. By merely avoiding that command, pop-up companies can get around much of the blocking. Adware companies generally remain unaffected by blockers, as their software creates windows from outside the browser.