Yeah, been there done that. The best was when I was in a meeting at work that included this mouthy lady who found out we were expecting our fifth and said "Man, what are you, MORMON?" To which I said of course -- "Yep!" She didn't have much to say after that Some people just don't understand we actually like having children.
I'm afraid it's going to be kind of like how GNOME and KDE were for a long time, two separate camps that can both run on the same hardware but don't mingle at all. This is especially true in this situation where the vendor -Nokia- wants a uniform, controlled experience for the end-user. The problem is they're trying to reinvent the wheel over and over again with their mail application, RSS reader, and so forth. There are so many lessons that have been learned by the developers of other, more mature applications that will need to be learned over and over again for the Maemo/Hildon desktop. I really feel they should have integrated existing top-notch applications like Claws mail and so forth to flesh out their suite. Even patching things to use Hildon customizations on their own would be so much less work that starting from the ground up.

This has turned into quite the post, but despite the good sense in re-using and integrating both desktop environments and applications I don't see that happening. If nothing else it would require a little bit of humility to say "we were wrong" and to work towards this goal of harmonizing these great DEs and applications and tossing the existing applications they've created.

Larry