Some weeks after BIS's announcement concering the release of OFP2 in late 2004 OFP.info has managed to get an interview with Marek Spanel who revealed at least some details/concepts for the upcoming sequel:

In order to speed up development BIS is trying to reuse as much code as possible from the current engine adding missing functionality and reworking parts that are not yet satisfactory to fit the future requirements. Good news also for mission- and addon-designers as the current concept includes maintaining the high level of support and communication concerning the ofp-community as well as even more 'freedom' when it comes to scripting or designing large-scale terrains.

The storyline and setting of the game still remain to be revealed not before the upcoming E3 but telling from the few pieces of teaser-material released so far I wouldn't be too surprised to see lots of jungle terrain and AirCav insignia ;)

Check out the original interview at ofp.info (link below).