Now, I try to stay out of discussions about who's following who and all that, since it's usually pointless and nothing good usually comes from it. However, after we changed our terminology from "pages" to "tabs" in Opera 9 to make it easier to migrate from other browsers such as Safari, Konqueror and the upcoming IE7, there are certain people who believe this to be evidence that Opera is "falling into line" or "following Firefox's lead".
After Firefox 1.5 was released to catch up with more Opera features, it does look like the Firefox team is learning from Opera again with Firefox 2. Not only will there be a close button on each tab just like in Opera, but it will default to tabs instead of new windows.
It's great to see that Firefox "falls into line" and makes it easier for people to learn about tabbed browsing – functionality that Opera users have already enjoyed for many, many years 🙂