The writings were on the wall with Opera Ice but now it’s official: Opera will move to Webkit entirely:
To provide a leading browser on Android and iOS, this year Opera will make a gradual transition to the WebKit engine, as well as Chromium, for most of its upcoming versions of browsers for smartphones and computers.
Håkon Wium Lie’s (Opera’s CTO) reasoning:
It makes more sense to have our experts working with the open source communities to further improve WebKit and Chromium, rather than developing our own rendering engine further. Opera will contribute to the WebKit and Chromium projects, and we have already submitted our first set of patches: to improve multi-column layout.
Logic move, yet I do hope we won’t end up with only 1 rendering engine in the end (history better not be repeating itself).
Opera, along with Mozilla, announced at a CSS Working Group meeting that we would support some -webkit prefixes. This is because through our site compatibility work, we have experienced that many authors of (especially mobile) sites only use -webkit prefixed CSS, thereby ignoring other vendor prefixes and not even including an unprefixed equivalent. This leads to a reduced user experience on Opera and Firefox, which don’t receive the same shiny effects such as transitions, gradients and the like, even if the browser supported those effects.
They’ve made some beta (labs) builds of their mobile emulator supporting -webkit prefixes.