No. Well, there is a "cost" of sorts associated with it. 'Expanded ISOs' can be made available through a simple selectable option. Its called an 'exanded ISO' because the camera is actually shooting at a lower ISO, under-exposing the image and then processing it to make up for the lowered brightness levels. The drawback of this is a noisier/grainier image so this option isn't useful to everyone or in all circumstances. The extra cost is extra noise.
BTW, this technique was called 'push processing' when done with film. It was sometimes done in emergencies when a photographer needed a higher shutter speed but didn't have a roll of high ISO film handy. The film was then 'push processed' by developing it for a longer amount of time.
I saw a release date of 28th Feb for the UK, but I'm sure I saw 11th Feb somewhere on Amazon.com yesterday (although I can't see that anywhere now).
UPDATE: a quick search on the web shows "March sometime" as being the current info. I think Amazon.com made a typo somewhere, hence I can't find it again.
Ah, the Rebel XT -- I had one of those for a while. Small LCD screen did make it a bit hard to check if something was in focus or not. The Canon 100-300mm USM isn't a bad lens. But you might consider upgrading the 28-80mm USM -- even the newer kit lens, the Canon EF-S 18-55mm f/3.5-5.6 IS, is an improvement. You might also enjoy working with a fast prime lens for the background blurring it can provide. Something like the the Canon 50mm f1.8 or 50mm f1.4 or 85mm f1.8 are excellent lenses.
Cool images, by the way!
Yes, old Canon EF lenses are compatible with the T2i although some old film-era third-party lenses are not 100% compatible. Plus the sensor in Canon's non-pro DSLRs are a bit smaller than film so you'll want to use and 18-55mm or similar standard zoom to cover the wide end (a 35-80mm lens would not be very useful on the T2i).