Playback from start instead of from current frame? I'm doing a smoke simulation right now, and I would love playback to start from my inpoint everytime I hit alt+a instead of running from the current frame.

Is that possible? 
Looking at bpy.ops.screen.animation_play it doesn't seem so....
Press Alt+A then hit Esc (while mouse in the 3d view) and then press Alt+A again to start from frame one. If this doesn't work you should open once your timeline and move once your mouse at frame one.