Apparently, you can't store 8,192,000 photos, at least not in Picasa Web Albums. Google's photo service has some strange limitations: a photo album can include up to 1,000 photos and a Picasa Web account can only have 1,000 albums. That means you'll be able to upload less than 1,000,000 photos, especially if you think that not all albums will include 1,000 photos.
Dave, a reader of this blog, is concerned: "Many people are upset that they purchased additional storage capacity from Google only to learn later that although they have plenty of free space, they have easily maxed out the 1000 files allowed by Google. Here is one of several threads on the Picasa help forum that discusses this issue. As someone who is/was considering purchasing extra storage space from Google in order to upload more pictures to Picasa Web Albums, I am a little concerned about this."
Of course, Google might say that the photos can also be stored using Google Docs or Gmail. Picasa Web Albums has to remove the limitations, improve photo uploading and the way you organize photos. Why do you have to upload photos to an album when Gmail and Google Docs use labels to organize messages and files?
{ Thanks, Dave. }
Update (February 28th): Google no longer shows the misleading message if you select 2 TB or more.