Google just launched a gmail download for your mobile phone. It works on a variety of phones as its a java app and only requires JVM. Don't know what a JVM is - no sweat. If you are having one of the recent Nokia phones - it will work just fine for you. The following screenshots are from a E61 phone . Oh yes - you also need a data connection like gprs for this to work.
The last screen shows how to turn of gmail from remembering your password. Usually you will not require it as the assumption is that only you will be using your mobile and will be signed in always. Unfortunately, I was using a borrowed phone as the Treo650 does not have a JVM and had to figure out how to make gmail forget my password.
All in all one nifty install and makes checking gmail all that much more easier.