It is not possible.

Lol, well, ok.... the XMLHttpRequest cannot send multipart/form-data, therefore, cannot upload files. There are two ways around this:
1) use an iframe. This can be transparent, e.g. using the dojo.io.bind will do it automatically.
2) use a pixel Flash movie. You can create a 1 pixel flash movie, interface with it using the external interface (Flash 8 required), and use the Flash buffer classes (Flash 9 required) to upload the file. The nice thing about this is that you get the total bytes transferred count, thus you can display an accurate progress bar.

I'll try to post an example of both options soon.

Brian Szoszorek wrote an excellent article on clearing trusted cache automatically with even gateways -- directory watcher.
Trusted cache should be enabled in every ColdFusion production server, as it prevents cfm,cfc files from being compiled into Java classes every time. ColdFusion will not check for file system updates, so you would have to clear cache every time you make a change. Brian proposed a solution to automate it via event gateways -- which only work for enterprise installs of course. Really nice I must say.

Microsoft announced that IE7 will be distributed via automatic updates. This will be very interesting to watch ... I hope they do some real testing before getting this bad boy out there.