A few points I can confirm from talking with Jud about this over the last few weeks:

- Billions is the correct magnitude. It's the result of Gnip's aggregation of multiple Twitter-firehose-scale feeds over a year. They are massive users of S3 storage.

- I'm unsure why he's using an XL instance in this case, but I know he's been experimenting heavily with different configs to improve performance

- How do you get sustained 700 deletes a second? I'm not being facetious, I see much slower performance using commercial and open-source interfaces to S3 like s3cmd or Bucket Explorer. I'd love to find some faster approaches.