Sniplets from Tomi Ahonens blog His site

"The year 2010 established a new record for new mobile phones sold, at about 1.37 Billion units sold. Bear in mind, that the world has only about 1.2 Billion personal computers and about 1.6 Billion television sets. But mobile phones sold almost 1.4 Billion new handsets just during the 12 months of 2010."

"Only about 750 million of the 4.2 Billion mobile phones in use, are smartphones or about 18% of all phones it the world."

So yes, we need mobile platform(s).
2010 22 % of sold mobiles were smartphones. Soon smartphones are likely to sell yearly even more than whole installed base of internet connected PC´s.

Mobile is priority. When developing programs adapting those to different userinterfaces should be norm.