According to the Guardian: "Google is celebrating the first birthday of its free email service Gmail by doubling users' capacity to two gigabytes, with a promise to boost its email storage further in future." Sounds good. But why does my Gmail page say that I have only 1479MB? Am I not worthy?:

UPDATE: Thanks to Robin and Mark for pointing out that Google is doling out the additional space a few megabytes at a time. I'm now up to 1540 MB, and there's a cute graphic on the Gmail login page that explains what's going on. To infinity and beyond, I guess.....
They seem to be doing it gradually (I have no idea why). You will find your number of bytes changes with each refresh. On the gmail home page (logout and re login) there is a counter that moves like a lottery ticker. I think this is part of an April Fools joke (the rest of the page is), but this part is lost on me.
Posted by: Robin at April 1, 2005 02:33 PMYou're right! I'm now up to 1527 MB!
Posted by: Geoff Arnold at April 1, 2005 02:43 PMMine is:
You are currently using 442 MB (27%) of your 1646 MB
The other strange thing is that for the past couple weeks, okay maybe 3 I seem to have lost a week, it has said you have 50 gmail invites left, as I send invites the number goes down to 45, then jumps back to 50.
Today it says just "invite a friend" but when you open it to invite someone then it says 50 left. I don't think there are any limits anymore.
Best guess based upon several years in IT:
Google has a vast global network of servers running Linux (www.computer.org/micro/mi2003/m2022.pdf) - currently being used to deliver fast search and other services (maps etc), based upon fastest “hop” to the nearest server.
As Google builds its infrastructure and these servers come online (and occasionally drop offline), the code behind the service identifies the available storage on a particular server, and thus the total global amount of storage varies.
As the company grows, storage media come down in price, and they invest further, the total volume of available storage is continuously increasing - thus the increase to an individual mailbox.
Google have been very careful in controlling the rollout of the e-mail service so they can leverage the total available storage, and record metrics for total average user e-mail storage.
It'll take some time to completely "map" the available storage across the distributed network, hence the gradual increase to your personal available storage. The 2 GB number given by Google was probably their best guess at the total available storage split between all current gmail subscribers.