The new deal will unfortunately segregate the NA and EU communities. EU players will not have access to NA servers with the exception of EverQuest II EU players already playing on them. This doesnt appear to work the other way around for NA players though.
Under the new partnership between SOE and ProSiebenSat.1 Games, European players of the above mentioned SOE games will be able to play via ProSiebenSat.1 Games's service and will not have access to U.S. servers. However, existing EverQuest II players in Europe that have played on U.S. servers before the transition will be allowed to continue playing on those servers through their SOE accounts.
European players will also be required to create a new ProSiebenSat.1 account to migrate their characters to. The upside is that the new deal will provide more localized support for the titles in question. Additional details are available in a new FAQ and more will be revealed at a later time.
You can read the official thread on the topic here. If the thread is any indication, there's quite a few unhappy about the move.
There's also an interesting story EQ2 Wire has put together that points out a few things that the deal may have overlooked. And some very good points. Check out the full story.
Thanks to wytchnocturnus for the tip.
Source: SOE Forums