The type of lens you are looking for is probably the Canon 28-135mm which translates to the 35mm equivalent of 49-216mm. (use a multiplier of 1.6 for Digital Rebel).
This lens has a close focus of 20 inches, but not true macro.
This Canon lens has image stabilization and sells for about $400.
It is possible that some of the other lens companies (Sigma, Vivitar, Tokina) makes a zoom lens with true macro.
Here is a link to all current Canon lenses:
My camera use is predominantly nature so I take both telephoto and macro pictures under varying conditions. If one were to buy the XT is there a single lens that allows the camera to reach the potential of its good quality sensor and do both macro and, say, 200 mm (35mm equivalent) telephoto? I don?t want to buy a good camera and then put a low quality lens on it. I thought about two lenses but then I have to carry a bag with the other lens in it? Is it possible to get a good macro/zoom lens that doesn?t cost as much as the camera? If so which one?