Dots Don't Matter in Gmail

I was quite surprised to read this post from the gmail team. http://gmailblog.blogspot.com/2008/03/2-hidden-ways-to-get-more-from-your.html

They say the dots in the middle of your gmail account don't matter. So you could be blog.reader@gmail.com or blogreader@gmail.com or even b.l.o.g.r.e.a.d.e.r@gmail.com and any of those variations will still get delivered.

This was a big surprise mostly because I sometimes get someone else's mail and I thought the difference was that I have a dot in my name and she doesn't. Now I have no idea why I sometimes get her mail. Just one of life's mysteries I guess.