Opera 10.52 RC for Win, Mac, Unix is reased, but this version exits many problems and may cause crash and loosing data or even can not to be used normally.
I do second on what rebecca_yan said. I am currently using Opera 10.51 and I could this is the best browser I ever tried in both speed and security terms. However, 10.52 RC is another case with a full of bugs and unstable.