Funcom officials have recently announced the details of the upcoming server merges, all of which will be performed in the next few weeks before the Christmas holidays. US servers Bloodspire and Hyperborea are the first to be merged, with more to follow soon. There are two forum threads on the topic, namely server merge information and server merge FAQ. It seems that Funcom are taking things seriously: the FAQ topic answers most of the problems that could occur during the merge and explains how they will be adressed. The resources guilds have spent on their battlekeeps will be reimbursed, for example, and the PvE guild cities will simply be moved. In case of duplicate character names, priority will be given to older accounts.
Funcom will also be offering a one-time character transfer service in the future for those unhappy with their realm for one reason or another. Interestingly, there will be no restrictions for moving between servers with different rulesets or even languages (except of course you won't be able to move your character between US and EU ones):
The option to transfer characters to another server will be available after all server merges have been completed. Every character will be eligible for one free transfer and this offer will be valid for one month after the final server merges have been completed. This transfer will be free of charge and can be used once per character and will be available from your billing pages.This option won't be available for entire guilds however, so if your clan wants to move, you will have to abandon your guild city and use the single character transfer service like everyone else.