Not only google but many other major companies use it. These big sites helped AJAX become popular but THAT'S NOT THE ONLY REASON why its getting so much of attention.
To improve user experience (partial page refresh), to develop RIAs, AJAX is the choice. Pluse nothing to install, nothing to download, no licensing cost etc. All of these are making AJAX popular and grabbing people's attention.
Ajax finally allows us to break the request/response paradigm of the web. By using a simple object (XMLHttpRequest) we can communicate asynchronously with our server allowing us a whole new freedom in creating really rich thin apps.
Nate Schutta<br />Coauthor of <a href="http://www.amazon.com/exec/obidos/redirect?link_code=ur2&camp=1789&tag=ntschuttacom-20&creative=9325&path=tg/detail/-/1590595823/qid=1127567332/sr=8-1/ref=pd_bbs_1?v=glance%26s=books%26n=507846" target="_blank" rel="nofollow">Foundations of Ajax</a><br />My blog: <a href="http://www.ntschutta.com/jat/" target="_blank" rel="nofollow">Just a Thought</a>