I just installed the Google Maps midlet on my T-Mobile SDA today and man is it great. You can get it at www.google.com/gmm I am a cop and am working in a new city and am still getting familiar with the streets. I got dispatched today to an out of the way street I had not been to yet. All I did was run the app, type in the street name and zip code of the city and instantly had the map. Could not be easier. Later, a citizen was trying to find a business but the business had recently moved. My lieutenant asked Dispatch to see if they had it on the CAD system. Before they found it I typed in the business name and zip code and Google Maps showed it on the map with the address and phone number. Dispatch never did find it.
The only problem I had was that either T-Mobile or Microsoft hides the Jave Midlet Manager (jmm.exe). After I closed the app the first time I could never find it again. So I had to unhide the files in the Windows directory with File Manager, then copy the jmm.exe file and paste the shortcut into the Start Menu folder. After that no problem.
I highly recommend this to you if you have not tried it before. Best of all it is free.