If the Qt route means that both Symbian as an application platform and Maemo as a application platform support a common language QT - then that is a boon - in the sence apps written for one platform can be easily ported to symbian platform with much more minor changes.

The cross-platform nature in the mobile sphere itself is a huge boon. Name one language now in the mobile world where you can develop an application and make it work on another mobile platform ? NONE.
(Of course not counting Java)

So this move seems more enticing from a developer perspective.
And getting a developer momentum is I believe the most critical thing in establishing a mobile platform as a standard.

Look where Zaurus (with its Qtopia), OpenMoko and Moto Linux got to without a big developer community behind it.
Even Maemo developer community is a niche community we have to agree.

So any effort to encompass a bigger development world is worth a try I believe.