The ease of mobile data could be the big talking point from Barcelona, so the announcement of Opera 9 Mobile is very timely. Promising widgets, multiple views of web pages (full screen, smart rendering, or intelligent zoom on a selected area), Jacva and Ajax support, the Norweigan company will be hoping that their browser is considered by all the major manufactuers. No release date has been given.
Since the new version is named version 9, this means that the rendring engine being used is version 9 (the Opera version numbering follows the version of the rendring engine of desktop Opera). Opera 9 on the desktop has quite a bit better rendring than Opera 8, so I would expect that most sites work flawlessly.