The Julie is reported to have a 4" screen and sliding QWERTY keyboard along with the standard WP7 goodies (1 gigahertz processor, multi-touch capability, etc).
Sony was mentioned amongst the many hardware launch partner when Windows Mobile 7 was announced during the 2010 Mobile World Congress. So the rumors aren't that far of a reach except Sony hasn't been a major player on the Windows Phone front. Maybe things are about to change.
Still, it would be interesting to see a Sony WP7 phone with Xbox integration. I wonder how the Play Station crowd will react.