El Presidente will permit pre-purchasing of Tropico 5 later today with both a standard and a Steam Special Edition on offer, with 10% off during the pre-order phase. Closed beta applicants get an additional 10% off.
Kalypso are offering three tiered goodies for Tropico 5 if enough pre-purchase orders are placed and they are Tropico 4, the first Tropico 5 DLC, and Omerta - City of Gangsters.
More details about the pre-purchase offers are available on the Steam. Tropico 5 releases on PC May 23rd, and on Mac and Xbox 360 this summer, PS4 this autumn.