As mentioned earlier, Opera Mobile 10 beta for Symbian Series 60 platform renders web pages accurately. This is thanks to the Opera Presto engine, which powers the desktop version of Opera 10. I ran the Acid3 test and it gained a 100/100 score - a very impressive score for a mobile browser even if it didn't pass the pixel for pixel likeness (not surprising considering the limited resolution). In comparison, the latest Firefox 3.5.4 has a score of 93/100.
Just for kicks I also ran the browser through the Acid2 test. The result, whilst not perfect, was still impressive.