The British Airways website is using Google Maps, making them potentially the first airline to create a Google Maps mashup. A section of their website promoting 'World Offers' (only departing from the UK) is now showing a Google Maps mashup of hotel locations for each city BA flies into. A list of cities is displayed with a "Discover hotels on Google Maps" link, bringing you to a map of recommended hotels with quick links for making a reservation. By checking on world cities that I'm familiar with it seems hotels are plotted in their proper location, even for those that don't yet have street mapping available from Google Maps. For each city the airport is clearly marked and for some cities (such as Paris) landmarks are also map-marked so you can find nearby hotels to these spots. Check out the mashup here..
Elsewhere on the site a Google Earth layer is available for download to show 111 British Airways destinations, including locations of hotels and prices. BA also uses Google Video to display the World Offer commercial that solely makes use of Google Earth throughout entire clip. It's worth a look. This is a great multi-Google-geo mashup that is sure to be an example for the entire airline and travel industry!
Google Maps Travel Mashups & Tools
UK Google Maps Mashups: Part 1 - Part 2 - Part 3
Google Maps UK Airport Hotel and Parking Mashup