OpenOpera Makes Opera Default Browser on iPhone
The moment Opera Mini for the iPhone was out, I downloaded it and have been using it as my primary browser since. Unfortunately, on the iPhone, you cannot switch your default browser to Opera. That is, until someone wrote an SBSettings plugin to change that. After installing OpenOpera from Rock App or Cydia, and enabling it, tapping links on your iPhone will open Opera Mini. Tapping on the address bar will paste the link.
One more thing is needed to use Opera as the Safari replacement on your iPhone: backgrounding. Both iPhone OS 4 and Backgrounder will fix that problem for you.