Google recently announced a new look for the GMail client on the iPhone (and Android).
The new interface is pretty intuitive, and pleasing to the eye. However, since GMail supports free IMAP, I use the built-in email client to check my email.
The new architecture involves more usage of the internal database on the iPhone to cache data. This reduces the number of calls to the server, which is more than handy when on EDGE or 3G. According to their blog, they’ve even implemented some HTML5 features.