Maybe I'm just behind the times but I didn't realise that Google Analystics could tell me how many visits to my site came from mobiles (Visitors / Mobile / Mobile Devices or Carriers).
Two things struck me when I looked. First, my data only appears after early October 2009, before that the mobile stats show 0. Is that when mobile monitoring started on Analytics?
Second, on one of my most visited sites, there was roughly 5% of visits from mobiles, increasing each month.
Is that about average? What do your stats say about mobile usage on your sites?