Well, I can't make iPhoto support XT RAW, nor can I tell you when it will. I do, however, have a workaround - if you have PhotoShop (may also work in Elements).
Get Dr Brown's Image Processor (free photoshop script) here:
http://www.russellbrown.com/tips_tech.html
This works with CS1 and is apparently built into the latest version of PS.
It gives you complete control over your RAW processing and then batch processes the files to JPEG (and/or TIFF and/or PSD). THe processed jpegs can then be imported into iPhoto. I have been doing it this way since long before iPhoto supported any type of RAW format.
iPhoto is great, and it is nice that they added RAW support. However, if you really want to shoot RAW on a regular basis, iPhoto is not the best choice to process your files. It does a good job, but a tool like PhotoShop (or the program that comes with your camera) provides a much higher level of control - which is supposed to be the point of shooting RAW. If you just want most of the settings to be "automatic" then you may as well shoot jpeg (which is actually a RAW file that the camera processes for you).
After doing that, you can save the RAW "originals" to CD/DVD/etc. to save space. If you really want to protect yourself, convert a set to DNG (Adobe's new digital negative format) and archive those as well. With all the different RAW formats floating around now, you never know what will be supported in the future. (Imagine trying to run iPhoto in "ClassicX mode" on your OS XXX system machine because none of the tools 25 years from now support the "ancient" Rebel XT RAW format!)
--Joe