Opera, Who Knew?
Precisely, who knew that Opera 9.1 does a better job rendering CSS than current builds of Firefox and the newly released Internet Explorer 7 (nope, not linking there)? Well, maybe you did but I'll wager most users had no idea and didn't even know they should care.
As Dan wrote previously, most webmasters are probably beginning to see Firefox gain on IE in their stats. In my opinion, that's great; IE is a mess, it's had a free ride for far too long and it's a real mule to design for . . . but is Firefox really the answer? Some jokers say NO, vehemently, Opera 9 has been getting some press for some pretty worthy feats.
Security
Opera has fixed all its known security holes while IE and Firefox still have 50%+, presently. Wha? And IE had you thinking that stuff was just for lamenting!
When I first read this I was pretty shocked to learn that Firefox was as behind as they are. Sure, it's only one data set and who knows how many undetected holes the little-used Opera browser has but, still, the fact that somebody actually went and fixed 100% something that was broken . . . swoon!
CSS
Have you heard of this Acid2 Test? No it's not chemistry-related and it doesn't have anything to do with hippies but it might alter your perspective. In brief, the Acid2 Test is a do-over of an earlier test using an HTML and CSS design to measure browsers' adherence to W3C HTML and CSS 2.0 standards; OK, one more time, it's this creepy smiley face that looks obliterated unless you're using a righteous browser.
I like this Acid2 test blog with pictures the best.
Conclusion
So, should you use Opera now? Well, no, I don't think so. Personally, I just don't like Opera. I think it's over-polished to the point it distracts from the content it browses (weird looking) and it flickers and I could never leave the tools with which Firefox blesses me every day. And, most importantly, our stats show that barely anyone else out there uses Opera. Right underneath MSNbot, Safari, Netscape (yikes), and something called Lanshanbot, Opera pulls in just 10 out of 8,534 sessions for a given set. Until Opera starts pulling up next to the competition, we have to keep designing for the broken toys. Sounds harsh but, rather than congratulate Opera, I'm just going to hope that the competition gets up to speed.

But, what do you think will happen when the W3C says that the next versions of XHTML and CSS are ready? Will anybody support the ARTICLE tag?