Using PA3's summoning ability, you can currently be summoned cross shard. No kidding! People are forming cross shard groups and farming Volan multiple times per day, GH's and DRRs freely. When you port, log or soul recall you are returned to your own shard.
While this is a bug, I think it's one that Trion should keep and maybe even develop it further into something similar to TERA's 'channel' system. Being able to move freely between shards might alleviate some of the latency issues, help with over or under population, and allow players to meet new people.