Sorry, I don't have any specific ideas, but the Small Cool Contest is running right now, and some of the apartments featured might be about the size of your bedroom, so maybe you could get some ideas from them?

I would suggest a system made to look built-in. If you took one or two walls and jutted out a shelf deep enough to work as a desk, then it can be your work space when needed but also look less desk-y at other times. Keep it open underneath, obviously so there's room to sit, but also so legs don't give it away as a desk. If the exercise equipment is always out because there's no space, put it all in cabinets installed above the shelf. Also put most of your office stuff there, and maybe in one or two base cabinets if necessary. In the shelf/desk areas where you have the computer and/or TV, get a door that can slide or be pulled in front of it so you don't see it when you're not using it.

If the room is big enough, you could float the bed and make a long, tall room divider that could serve as the headboard on one side and provide shelves for the office on the other. I did NOT do this in my room and find myself lying in bed staring across the room at my messy bookshelves. Sigh.

Depending on the proportions of your room you may be able to use a curtain to conceal an office "wall" of desks, tech etc. I have this in my bedroom, with a semi-sheer curtain hung from a suspension rod. The fabric keeps the look soft enough for a bedroom but completely conceals the office function. Mine is literally a nook, but you could easily do it with a whole wall.

We are in the process of building a small home office into a very small space in our bedroom. It's about the size of a closet, but it doesn't have the framing of a closet. I'll try to post some photos on flickr then come back here and post links.

Definitely some sort of divider (like a bookcase wall/cubical from IKEA). I would put all of my focus on making the bed area be simple, clutter-free and restful (and near a window).
-Laura

I put install a long desk along one wall that you can use two chairs on, rather than two desks. If possible, have it kind of "floating" so you can store the exercise equipment under. For the TV, you could put it on this desk, or mount it on the wall.

it is not a good idea to combine so much in a master bedroom. Bad fung shui, really. If the room is large enough then divide and conquer. I do like the idea of a headboard as a divider with the work/excerise in one concealed area, then the bed/sleeping area in the other.