Obviously you can now ignore the dots (if any) in your Google account name when logging into GMail: http://googlesystem.blogspot.com/2010/04/dots-no-longer-required-when-you-log-in.html
It also seems that this "feature" has been available for some time according to that blog post.
I originally have one dot in my GMail address. I have tested logging in without it, and it works. I also tested sending an e-mail to the address without the dot, which also works. I even tried logging in adding both one and two extra dots in random places in the address - and even that works.
I can't say it is very useful, but at least it minimizes the risk that somebody misspells/mis-sends your e-mail, and that's a good thing I guess :)