I've had a chance to use the Wireless@SG connect app and it works.
I downloaded the SingTel version but I don't think it matters which of the three apps you download.
When you run the app, you have to fill in all the relevant details (provider, domain, username and password). The app then fetches a new configuration profile that you have to install on your iPhone.
You are then prompted to input your password again. And that's it. With this new profile, each time you enter a Wireless@SGx network, you will be logged in automatically.
Note that the profile will only log you in to a Wireless@SGx network. The additional 'x' signifies that the network supports Seamless and Secure Access.
I tested this by logging on to one Wireless@SGx network at my office. I then walked over to the nearby mall. My iPhone detected the new Wireless@SGx in the mall and automatically connected me. Pretty sweet. Looking forward to September when all hotspots will be enabled.