I was actually one of the original invitees (or a very early one anyway). I use Google all the time and one day I opened up the search engine, which is my start page, and there was a link asking my if wanted to test the new gmail; so of course I said Yes. BTW, still have about 40 invites if anyone interested--although they are pretty easy to find, just Google it

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What I love now though, is the new personalized start page. If you have GMail, then you have probably seen this. Now when I open the Google start page (search engine), I can add personalized content to the page--such as new headlines, local weather, quote of the day, and (most impressive and convenient) my new emails. Adds just the content I want, and is still very simple and uncluttered.
Once you have your account set up, you will also notice that Google remembers your past searches and refines its search to meet your needs based on the sites you visit. This is great, I will have to troubleshoot a problem and be like "I know I just had to look that up a couple weeks ago, and where was the site where I found the answer". Sure enough they find it every time--with a time stamp of when I last visited the site. I don't mean to sound like a salesman, but I just love that my Google mail account has turned out to be so much more. If you still use Yahoo! or others, I recomend at least giving this a try.