again, already done in retail (a little) where FS1 required a minimum difficulty level of medium for at least two of the medals.
i don't get the big deal with achievements. i have no desire to see a popup flash on my screen every time i rack up 10 more kills. i know i beat a level. a little badge telling me that i did is just dumb. and if it's for an easter egg, better off NOT advertised through an "achievement".
Achievements just for playing the game normally are kind of pointless, but the completionist in me likes hunting all of them down, especially when they involve playing through the game in an unusual manner. There was a fun one from HL2: Episode 1 that involved firing only a single shot throughout the entire game, and relying almost solely on the Gravity Gun to kill things. (And then there was the gnome one from Episode 2...*shudder*) You could do something like that in FS by tying achievements to some of the more difficult bonus objectives, like the aforementioned perfect run on "Bearbaiting," or saving all four escape pods on "A Failure to Communicate." Hell, you could even set things up for speedruns on certain missions, or for completing a mission without using your primaries once.
All this is hypothetical, as I sincerely doubt that Interplay has the resources to do more than just plop FS on Steam as-is. Even that would be great, though, since as much as I love GOG.com, Steam obviously reaches a much bigger audience by default.