Norwegian company Opera Software deals in similar browser development for more than 10 years. Version 7 presented completely modified Presto engine that is used now too. The latest serious modification was in December 2011 when Opera 11 was released. Now the index of the version grew up to 11.51.
New Peregrine engine is started from version 10. It brings a lot of modifications and updates. Among them is the support of HTML 5 that is not completely developed. Now the team of developers deals with version 10 improvement.
The other day Opera 11.51 was released. The main modifications are the security bug fixes.
It is possible to download 11.51 for various operating systems and on the various languages on the official page of the browser: