As part of the iPhone/iPod Touch 3.1 Software update released yesterday during Apple's rock and roll event, Mobile Safari gained anticipated anti-phishing features currently present in its desktop version. However, security firm Intego is criticizing the feature's inconsistency as being worse than if the feature hadn't been included at all.
We've had a number of people test [the anti-phishing feature], and some people get warnings for sites that others can load just fine. We've tried isolating locations, iPhone/iPod touch models, and whether they are connecting over a cell network or via wifi, but all we've come up with is that sometimes it works and sometimes it doesn't. This is clearly more dangerous than no protection at all, because if users think they are protected, they are less careful about which links they click.
The desktop version of Safari uses Google's Safe Browsing API. It's unclear what technology the Mobile Safari browser uses and what the exact reason is for the inconsistent results, however Intego as well as other researchers promise to continue to investigate the issue.