With all the hoopla around node.js and threadless concurrency it’s only to be expected that we would see similar (but different) efforts. Vert.x is one of these efforts.
Since a vertex is a synonym for a node in graph theory, it’s fairly obvious that imitation is the sincerest form of flattery. I’m still not a huge fan of the event loop as a general concurrency strategy (as I wrote here) since it requires that you know what sort of requests you are getting. I think it’s ideal for systems concurrency rather than general concurrency since you need to know about the request before your can deal with it but it’s apparent that your mileage may vary as Node.js has proven insanely popular.
Anyway, vert.x boasts better performance (yes I know; lies, damn lies and microbenchmarks!) more languages, as many features as Node.js and even a compatibility layer so that you can run your node applications on vertex with zero changes (allegedly). The only thing it doesn’t have is the amazing community support of node.js but it certainly looks interesting.
It looks pretty interesting so why not go have a look at http://vertx.io/