If you can provide auto-builder logs that would probably help some more tech savvy people.

I've had this happen when trying to package with iw. I just charged Architecture from "any" to "armel" as a temporary workaround. It completely ignored the i386 build, but that's not used on the N900 anyway.

Also, do you have the right repository (presumably, Extras-Devel, not just Extras) enabled on your device?