Linda asked: How current are the satellite images?

Answer: This will depend on where you get your data from most importantly.  The satellite data from the ESRI Resource Center is old for certain layers but they also have a Daily Image layer from the MODIS satellites which is as current as anyone outside the CIA or NCIS can get! Some other data sources are a few years old- the web mapping sites like Mapquest and Virtual Earth can be old for certain parts of the world but new in others. It is often necessary to dig deeper to find out the currency information- this is part of the metadata for any spatial data and it's important that you keep your own metadata current- if you source some imagery make sure you update the metadata with your source contact details, currency dates, accuracy and use restrictions. Google Earth now has a temporal feature where you can change the time period for what you are viewing- so you can see satellite imagery changing over time! Very powerful.