Guild Wars 2 beta: The answer to the most popular beta question

Yes, your beta characters will be deleted. Sorry. From the ArenaNet blog:

Before and immediately following this final Beta Weekend Event we’ll delete all existing beta information. Every beta character and all information or items associated with them will be deleted before Headstart Access and launch occurs. However, we will be preserving your beta account’s contact list so you can easily connect with your fellow beta gamers during Headstart Access or after launch.