I say, do it enthusiastically. She might follow your lead. I put my infant son (3 mos) to bed in a crib in his brother's room (then, 24 mos), and they loved being 'bedtime buddies'. There was a short period of adjustment as they got used to new nighttime sounds, but I found that they both slept better when they were together than they ever slept alone.
So, talk it up and let your 2 year old have some say on how to get the room "ready" for sharing. She might have some great ideas.