Anne posts in his blog that internal builds of Opera that are intended for some post-Kestrel release are already at 98/100 of the Acid3 test. You won't have to take his word for it either, as we are apparently planning a public build to demonstrate this.
So yes, a lot of things are going on behind the scenes. While Kestrel might be the "latest and greatest" public version, we have people working on the future of Opera as well. And if you like the various improvements in Kestrel I think you'll be pleased by the version after Kestrel as well.
Update: Looks like it's actually 100/100 now!