If you alraedy had a blogger acount then they rolled out gmail to them today. So you might have to keep looking at that blogger sign in page a link will appear asking for whether you want to sign up for gmail http://slashdot.org/articles/04/04/25/1438250.shtml?tid=126&tid=95 Not all blogger users have been invited. And people who are joining blogger now after the announcement are not getting accounts.
for those who aren't aware, google will be reading each and every piece of email on their service. they aren't running this service for the love of humanity...
disk space is cheap majority of people wont use 1gb text/html compress down easily so while the uncompressed space would be 1gb the compressed space is a whole lot less