Through the means of the Opera Desktop Team's blog, a first alpha build of Opera 10.6 has been made available. Although minor its version increase, it does offer some interesting tidbits.

I guess the most important promise coming from Opera Software is that Opera 10.6 is the very first synchronous release of Opera in a while, meaning it will be simultaneously be released for Windows, Linux and Mac. But there is more! Carakan in Opera 10.5 was a big first step, a direct confrontation with V8, leaving behind Nitro (Safari) and TraceMonkey (Firefox). In this release Carakan has been improved even further, causing a noticeable increase that possibly beats Chrome 5's V8 update.

Other changes include UI tweaks, such as "menu" text next to the "O" button on Windows in the top left. This button, as the label suggests, holds the replacement menu for Opera (although you can swap back to the traditional menu bar as well). Other tweaks include widescreen thumbnails for Speed Dial, nicer animations when hovering tabs and their thumbnails. For the Mac more Carbon was removed (and dynamically loaded) leading to better performance overall.

You can test this early build by downloading it from the Opera Desktop Team's blog, be sure to leave some feedback for them to find!