Opera 10 alpha 1 released yesterday and it passed the acid test 3 with 100/100. See some more additional features
Presto 2.2 Engine
Performance boost
100/100 and pixel-perfect on the Acid3 test
Auto-update
Inline spelling checker
Opera Mail improvements, including rich text composition and delete after X days
Widget Improvements on Linux
Read more and dowmload (remember it is an ALPHA version)