Who'd have thunk it- maps being the next battleground after search?It has the usual suspects fighting for mindshare- Google, Yahoo, Microsoft and even Amazon (A9).
Web based mapping providers have been around from the beginning of the web- I remember using a service called 'MapIt' back in the mid 90s. Soon afterwards, MapQuest and then Yahoo Maps starting providing the same.
It wasn't until Google came in that maps become sexy again. Google has been able to take something that has been around for a while, redo it in a much better way, and create excitement around it. It has done it with search, with email, and now maps.
Other than a really well done interface, Google was able to get developers excited about maps to such an extent that it spawned the unfortunately termed, but incredibly exciting 'mashups' (see Chicago Crime and Free Wifi for examples). The earlier mashups reverse engineered Google Maps, though now Google has released a documented API.
Yahoo too has released its API, and its own catchup mashups (For eg, SF Dog parks).
This kind of stuff is the future of Web services, but more on that later.
Google then upped the arms race by first adding a satellite view of maps, and then a neat 'hybrid' view that combines both. Finally it added Google earth and a limited Google moon. It was now Microsoft's turn for catch up with Virtual earth
And now A9 maps has the latest new 'feature'- street level maps of major cities, and has a fleet of trucks taking pictures of the rest of the country… ambitious to say the least. I remember reading about Google experimenting with similar technologies- I'd guess we will see something similar from Google sometime soon.
What's at stake here other than who has the coolest technologies? Geographical searches and map visualization has a lot of interesting applications, and many with a lot of commercial value. The first and obvious one seems be to local search + yellow pages.