It seems that Google Earth application is not available in all regions. If you cannot find it in the Android market, then you can download Market enabler and change the market region to US.
- Download and install market enabler application (check this post for more details
- Backup your current region settings in market enabler ("save current settings" button in market enabler)
- From market enabler, "settings list" tab, select "[us] T-Mobile (T-Mobile)", press and hold over it until you see the "fake this provider now" popup.
- Go to Android market and search for Google earth. If Google earth doesn't show, then you might need to force-close android market application and search again.
- Switch back to your original region in market enabler (In market enabler, click the "restore settings" button)