Caching like Bill outlined would work well to share the data, even if you used some kind of Inter-Module Communication you would be doing effectively the same thing.

Keep in mind though, that the more modules you have on a page, the more you are going to affect performance by adding overhead in the back-end, mainly because of permission checks, and while you are logged in as someone with edit rights, it means the actions menu also will be built four times instead of one.

Unless you have a reason to put parts on different pages, I would suggest trying to do it all within the same module.