Gut feeling is "enhanced" = a more polished version of the more popular mods and tweaks that exist (plus another area and companion NPC or whatever, which exist in spades in the fan community), with updated BG1 UI.
It's a great business move. Judging by fan reactions that I've seen, many are willing to throw $20-30 at Beamdog for what very well may amount to things that have existed in the modding community for free for years.
As somebody else has brought up, it's also a great way for Beamdog to get their download/DRM client on a lot more machines.
I'm hoping the mod community stays active with the pre-Beamdog games, and will attempt to emulate some of the changes with mods if they're good/interesting, because if my gut feeling is right I'll probably end up passing.