Yes, the people over at dotDigitalBlog have noted in a blog post that no less than 7% of email opens happening on their platforms are being done with iPhone. In contrast to that, other mobile platforms like Android, Blackberry and Nokia don’t seem to rake up as much usage as the iPhone. Also, Outlook 2007 outperforms Outlook 2010 by a 15% vs 1,5% share, which is quite big, seeing as Outlook 2010 was launched nearly a year ago.
Next to that, on the browser front there seems to be more sharing of market share going on: Internet Explorer 7 going down while Firefox and Chrome usage keep on growing. Good news for Internet Explorer 6 haters: it was down to 0,7% from 1,2% in January.
These are only figures from the dotMailer platform of course: consult with your ESP for usage figures of their platform, or even better: your specific contact base. As with everything, and especially in email marketing, your mileage may vary.