Today, Blizzard introduced paid PvE to PvP server transfers. Previously, if you had a character on a PvE server, you could not transfer that character to a PvP server. A character on a PvP server could transfer to PvE, but it was a one-way trip.
I am oddly mixed about this development. On the one hand, I've levelled a character on both server types, and the experience on a PvP server is very different. Unleashing hordes of carebears who think they're something special onto a PvP server, and letting them gank without having had the experience of being the gankee ... well, something inside me rebels at that thought.
There is a certain type of player on PvE servers who is very boastful about PvP prowess. The type of person who'll kill a lowbie Horde who's flagged accidentally, or gank an obviously-AFK Alliance Holy Priest sitting outside a raid instance*, and then start to brag about how "leet" they are. And you sit there and think, "So why aren't you on a PvP server? Oh, that's right, because you'd get beaten into the ground by people who know how to play." The PvP realms are going to plagued by this type of player.
*This was quite funny when three minutes later the entire Alliance raid boiled out of the instance, fully flagged, and proceeded to wipe out every flagged Horde who had hurt their priest. As I was not flagged, this brand of karma amused me greatly.
But on the flip side, the division was really hurting the raiding guilds on the PvE servers. For some reason--probably because Achiever/Killers tend to be very good players--the best raiding guilds have always been found on PvP servers. This has made it very hard for PvE guilds to recruit, as PvP people will not transfer, not even for a trial, because it's a one-way trip. More and more, high end raiding is coalescing around the PvP servers, and that is hurting the PvE servers.
I think the turning point came with the guild Juggernaut of Doomhammer. Juggernaut was one of the premier guilds on a PvE server, but they were having serious trouble recruiting for Sunwell. They managed to get Kil'Jaeden down to 30% before giving up. The entire guild rerolled on the PvP server Mal'Ganis as Juggernaut II. Juggernaut II blew through the raiding scene and downed Kil'Jaeden four months after rerolling.
Maybe if the high end hadn't been so slanted towards PvP, things would have worked out. If the best guilds were distributed evenly between server types, maybe the wall could have been preserved. But this change was probably necessary in order for high-end raiding to survive on PvE servers.
On a personal level, this change has affected me. Three months ago, I was invited to join a raiding guild on a PvP server. I liked the guild, but as it was a PvP server, I ended up making another paladin on that server. I've tried to level it, but my heart really wasn't in it. I managed to make it to 55.
The thing was that this new paladin wasn't my main, and that turned out to be really important to me. It wasn't the paladin I killed Ragnaros and Nefarian with, the character that I've been playing for multiple years, wasn't the character I played back when we had Seal of Fury, the character that was in Defender of the Crown, the character with all my keys and attunements and my Knight-Captain title, my 8/8 Lightforge, and the character I learned to raid with. Yeah, they're not exactly impressive achievements, but still, it was my main, and that ended up meaning a lot to me.
So I've been levelling this new paladin desultorily (also, paladin levelling is extremely boring, which didn't help) and had been slowly realizing that I didn't really want to play a new paladin. That I wanted to play Coriel. Then this change was announced. The first thing I did upon coming home was to delete the new paladin and transfer Coriel to the PvP server.
So in the end I'm not sure what to think about PvE to PvP transfers. I somehow don't think it was a good change, but it may have been a necessary change. And it has allowed me to continue to play my main into Wrath of the Lich King, for which I am very grateful.