M.S.
Make your room boring and her room awesome. A big girl bed in sheets she picks out, a fabulous nightlight lamp (princess theme?), adhesive glow-in-the-dark stars, and all of her toys in her own room--NO toys in your room. Take that toddler bed and get rid of it--but put the mattress under your bed for those middle of the night visits that you KNOW are going to happen (at least at first). Night music CD, preferrably the same one she's listened to in your room (or no music, if that's what she's used to).
Depending on your daughter's temperment and capacity for change, introduce these changes slowly or all at once...you'll know what to do.
I'm not sure of her maturity level, and 4 is a bit young for this, but maybe she'd like a sleepover with a pal or cousin. Basically, make her room "hers" and make having her own private, special place exciting and even fun sometimes. Make your room as boring as possible....to a 4 year old, not your husband (which when you lose the kid, might get a whole lot less boring for the two of you)!! Good luck!