I saw a talk by the director of the spitzer telescope institute at work a couple of weeks ago... it was a relavation. I had never appreciated what an amazingly powerful tool it was... he showed one picture from an optical telescope where part of the sky was blotted out by a dust cloud, then showed us a picture from the Spitzer telescope of the same area... it saw right through it showing what was in the cloud, and beyond it... additionally, it can detect chemical compositions of nebulae and galaxies... it can look at a galaxy and pinpoint where new stars are being formed...

This telescope promises to be as important as Hubble, unfortunately it has a lifetime of only a few years, due to the fact it uses liquid helium that is slowly boiling away, and it cannot be serviced due to its orbit...

This is just the beginning of what it can do... it looks at wavelengths that we cannot probe from earth (3-30 microns) because our atmosphere glows in those wavelengths due to its heat... It will see things we never could see before...

It is an amazing device.