I doubt it would be for maemo5
It would likely be for maemo4
hildon to gnome was the last I heard of work being done on it...
https://wiki.gnome.org/Attic/Hildon/Building
UME is another alternative...
https://web.archive.org/web/20070613....net/book/2/1/
Moblin is prolly more current than the preceeding
I think meego is prolly the last to recently run on "other" handheld devices than maemo...
there is this for buntu...
https://blueprints.launchpad.net/ubu...top-for-ubuntu
a little old...(2007-ish)
there is this for debian!
aha! little more current...squeezy...
https://packages.debian.org/squeeze/hildon-desktop
yet again I think it is more of an earlier maemo desktop than maemo5 though...

Maemo5.. even Maemo4... would be fine...but earlier?...
naw...too rough..for the desired outcome.

Best bet is...
you could pilfer moises maemo5 work for what is needed...
https://www.youtube.com/watch?v=RuIrRoRPufc

There is of course another option I just thought of...
rip the ui out of the latest linpus lite...
That definitely comes closest to our ui....
very touch friendly...
has the maem-esque look and feel...
based off a very very modified version of cinnamon (i think) and moblin 2 originally...
meant for big or small screen...
Linpus lite is a sparse os with not alot of software (compared to some os's)...
but the build structure of it's ui...it's desktop environment is...(what's good words here)...familiar and cozy...yeah...
that alone makes it into my "odd-ball" favourite distro pile short list..
I like to use now and again...

I have a small folder of pertinent urls and files on this topic..
I do not believe age being a factor since the wealth of experience from each of the attempted or successful methods has value...
Never know when something old ends up having validity in the present....

As far as course of direction to take considering the desired outcome....welllll....that is the question ...
As far as windows phone, iphone, even android...I am COMPLETELY ignorant of the respective operating systems ...never having desired to have (in the past) one....I never bothered to learn...as far as distros for handheld...it has been maemo based for me from day one...
so I am quite clueless pertaining to what could, would or should run on any of those devices...
Now...
get maemo running on android ...properly....
and I will rethink my philo.
pick up a competitive device and continue on quite merrily...
Come to think of it...
if maemo ends up running on droid....
think of the number of android converts we could get ....
...