I wouldn’t say any of the new Nokia Windows Phones (Lumia 710, 800, 900) use ‘old’ hardware at all. You have to realize the WP OS currently doesn’t support dual/quad-core CPUs and has a fixed screen resolution (800x480); so if that’s what you’re referencing, I’d say that’s not a case of slow development cycles but a limitation of the OS that Nokia must abide by.
And what’s the value in just looking at something purely based on hardware? What should matter is how it performs. WP is optimized to work with the minimal hardware specs MSFT has called-for and is remarkably snappy with it's single-core processers, and gets great battery life, so how would ‘newer’ hardware add-value here?
So, given the above, what ‘cutting-edge’ tech would you have them add? Resolution aside, the Lumia 900 has one of the best screens around, it’s 4G, I’d say it has the best offline navigation around (Nokia owns Navteq after all), and I’d say the phone's design itself is pretty cutting-edge as well.