Kathyn Cramer, based in New York, is doing great work with Google maps. The following information is quoted from her blog.
Step 1: Go to Google Maps and enter the address. Click on the button that says "Hybrid" on the upper right. You will get an image with a speech ballon pointing to a thumbtack showing the location of the address on the satellite photo. [IMPORTANT UPDATE: Bless their hearts, Google Maps has added a "KATRINA" button to New Orleans areas searches, so they have automated some of the process I describe here! Yee haw!]
Step 2: Click up and down the vertical ladder-like bar to see the image at various scales until you feel you can find the place on a satellite image.
Step 3: Compare your image to this superimposition of the FEMA flood map on a New Orleans satellite photo, created by the Google Earth Current Events Community. Here is a small version. Click on it for a much bigger picture.
If the address you are checking is fairly centrally located, you can also check your address image against the DigitalGlobe satellite picture of the flooding.
For more detailed instructions, visit her blog.