Obviously you'll need a jailbroken phone for this -- what, you didn't think Apple would actually let you dump Safari if it hand any choice over the matter, did you? Then all you'll need to do is fire up Cydia and search for an app cunningly called "BrowserChooser".
Open BrowserChooser and tap Chrome to set it as your default browser -- that's it. Every time you click a link anywhere within iOS, Chrome will launch instead of mobile Safari. Now, if Apple would just gift Chrome with the Nitro engine, we'd really have a Chrome to love on our iPhones. [iMore]