It is like 2001 all over again: pop-ups are back… (over at Dan Gillmor’s blog):
Most of the pop-ups that get through now are using a hole in Flash that let’s Flash open up a new window. Download and install a flash blocking extentsion from the mozilla site to fix this. This has the added bonus of not auto-playing any flash, but letting you select which flash displays you see. The bonus here is that in addition to pop-ups you’re also not forced to see flash ads unless you request them.