Our mobile browser is so portable that a bunch of guys in our Swedish office decided to port it to Maemo (Nokia N800/N810/N900) on their spare time!
As a special treat, this is the first version of Opera Mobile to include Carakan, Vega, and Presto 2.5. it is perhaps thanks to these three that intial feedback indicates that it's much (or at least noticeably) faster than both the standard Maemo browser and Firefox.
Since it is not an official product, there are some rough edges, and there's no guarantee that it will ever be released as a final product. For example, plugins are not suported, and JIT is not enabled in Carakan because it's too unstable. Take a look at the list of known issues for more information.
If you have a Maemo phone, take Opera for a spin, and let the team know what you think.