IMO the key with eventual consistency is making it known which bits are currently known to be consistent, and which are still in flux. I realize that this is vague, but how that works depends on what it is you're processing and how much time it takes for consistency to emerge.

If you're doing any kind of Important Reporting on eventually consistent data, you'd better make sure that you either know you're only including finalised data, or that there's a big fat warning with error bars.