Google needs to give people a compelling reason to try out the service. Remember when GMail launched in 2004 and 1 GB of storage space for e-mail seemed crazy? I think Hotmail offered 4 MB of space at the time. You had to constantly delete old e-mails to keep below the quota. Storing files in the cloud is reaching a tipping point where it becomes mainstream. Google needs to get a foothold now if they want to be the leader in this product category.
100GB is on the outer edge of plausibility. 10-20GB would be reasonable. One is definitely not enough.
https://accounts.google.com/b/0/PurchaseStorage
I'm currently storing all my backups as tar.gz files on Google Docs and am even able to upload multiple-GB files via my browser.