This a Dev Blog, about EVEmail finally becoming usable. That's pretty much it.
OK, ok: that's a big deal, for we're coming a long way on this one. So here's the skinny:
The new EVEmail, barring overlooked bugs, will do what you'd have expected it to do from about day one of EVE, but not just that.
Through linking to API and client-side storage, it will make EVEmails, mail alerts and mailing lists a convenient enough exchange medium that we may actually use them.
It's like getting tap water versus a crank-and-bucket well in the backyard: it's only a few paces closer to home, but that's a huge difference.
So, all together: Yay for new EVEmail !