I have a room in my game I would like to zoom into before the room opens then slowly zoom out after the room starts.
You can put a screenshot of the room in a DynamicSprite, then resize & crop a copy of that and put it on a GUI.
As soon as the zoom factor reaches 1.0, turn off the GUI.
There's no way to zoom a room directly.
Damn. Well it cool its not that important. I wish I could that but I think I want it to rain in this room so that wont work.
One thing to consider is that if you're stretching the image it would also then look like hell (depending how large your zoom factor is)..so you might even consider using an external application to create a copy of the room at the maximum scale, import that as a sprite into AGS, and then shrink it using the DynamicSprite functions. Down-scaling images is always better than stretching them because then you're just losing data instead of trying to create new data out of thin air.
And the GUI approach isn't strictly a bad idea..but if you're planning on running other effects then things could get messy.
Why don't you just make a video, like in the PSX Final Fantasy games. Play an animation which last frame is identical to you'r room so it will look like there's no gap between video and game graphics.
As far as I remember, DDDDD (http://www.adventuregamestudio.co.uk/games.php?action=detail&id=529) did this at the beginning of the game and it worked.