Opera 9.61, a security fix release for the 9.60 stable version, was released yesterday, October 21, 2008. This security release fixes several problems concerning the user interface as well as a few other security bugs. The full changelog is available here.
Opera is a closed-source, full-featured web browser for both Linux and Windows, built in Qt 3, which also includes an IRC client and a BitTorrent client. Each release is packaged for all the major distributions, like Debian, Ubuntu, Fedora, Gentoo, Mandriva, SuSE, Slackware or MEPIS.
To install it on Debian or Ubuntu, download the DEB package from their official website, here, and use:
dpkg -i opera_9.61.2456.gcc4.qt3_i386.deb
sudo dpkg -i opera_9.61.2456.gcc4.qt3_i386.deb
With your user's password.