According to RiftJunkies.com, players logging into Rift are being presented with a Message of the Day indicating that servers are being merged or turned into trial servers. Players are then given a suggested server to move to but can move to any currently active server.
PVE Belmont –> Millrush Galena –> Millrush Atrophinius –> Greenscale Crucia –> Greenscale Alsbeth –> Shatterbone
PVE – RP Estrael –> Faeblight Shadefallen –> Faeblight
PVP Sunrest(PVP-RP) –> Deepstrike Freeholme –> Deepstrike Dayblind –> Deepstrike Faemist –> Briarcliff
So far no official word has been released on the Rift forums but we'll keep you posted.