I think their biggest challenge with going down the MeeGo route would be acquiring the kind of App ecosystem that iOS and Android have. I reckon their best bet would be to implement something like Alien Dalvik[1] to allow very easy porting of existing Android apps to MeeGo, and make their 'app store' as seamlessly alike to iOS and Android's (including working with top app developers to encourage them to bring over the most desirable apps).
Once they can be seen as having the same big name apps as the other two, I think MeeGo has much more of a chance of being competitive, rather than being a 'third world country' of a platform.
While that is certainly true, MeeGo is much more of a linux system than android is, and has great potential to attract hackers. The same tools and libraries can be used to develop for MeeGo, as is used in any (desktop) linux distribution. My point is, there is a lot of developers out there that already know how to develop for MeeGo. Not a proprietary but only very lightly platform specific tool chain is needed.
Once they can be seen as having the same big name apps as the other two, I think MeeGo has much more of a chance of being competitive, rather than being a 'third world country' of a platform.
[1] http://www.allaboutmeego.com/news/item/12571_Alien_Dalvik_ho...