The most notable and requested change grants all tank stances 100% threat generation. "We've received a lot of feedback from tanks regarding how easy or difficult it is to hold threat on various encounters," Peckenpaugh explains. Then he clarifies by saying that single-target taunting will generally remain unchanged, but because of "smart" AOEs that avoid crowd-controlled enemies, AOE-threat generation should improve significantly.
Secondly, BioWare is well aware of the population issues on a large portion of servers. That is why on June 12th, the team will begin the free character transfer service. In a soft server merge system similar to the one implemented by Star Wars Galaxies, BioWare will open up specific servers as origin servers and others as destination servers. To help BioWare maintain a bit of control over the situation, the transfer precess will be "gradual and staged," according the developer blog post.
The specific details regarding which servers will be affected have not be released yet, but rest assured that Massively will let you in on the latest details when they become available.
[Update: Community Manager Joveth Gonzalez gave more detail on the official forums about how the origin and destination servers will work: "In order to ensure an optimal playing experience for every server, we'll be offering direct transfers from one origin server to a pre-selected destination server."]