Eons ago SUN systems proclaimed that "We are the dot in .com" which has got nothing to do with this post. Except for the fact this post talks about the dots in Gmail.
As per this entry @ Gmail Blog, the dots are insignificant in Google's grand scheme of user ids. For this periodic loss, Google gets benevolent and allows extra pluses in your identity. It all evens out in Googlic form of justice. World is not fair, they are +f.a.i.r. And lovely, no!
For some body like Mallika Sherawat has ID say email@example.com, it can also be represented as firstname.lastname@example.org
So much fun this is.