Google has posted a small guide showing how developers can add this functionality to their iOS app.
First, you need to add a bit of code to find out if Chrome is installed on the iPhone or iPad. Then, you can make your app use one of these two, to open links using Chrome
- googlechrome for http
- googlechromes for https
To actually open a URL in Chrome, the URI scheme provided in the URL must be changed from http or https to the Google Chrome equivalent, the guide says. If Chrome is installed, the code converts the URI scheme found in the URL to the Google Chrome equivalent. When Google Chrome opens, the URL passed as a parameter will be opened in a new tab.
Find more details and the sample code here.
via Daring Fireball