[UPHPU] Tracking Mobile Visitors

[Craig Jackson]

UPHPU,
I am interested in seeing if that many visitors to my sites are from
mobile phones. If there is a big enough percentage, then the sites
should probably get some tweaks to make sure they are visually
appealing for mobile phone visitors, as well.

Which leads to my question of what is the best way to differentiate
visitors from normal sources to visitors from mobile phones? Is there
an analytics system already available that does this? Can I pop in
some PHP or Javascript magic? Or, can I determine this through the
Apache log by grabbing User Agent info?

Thanks for any info,
Craig Jackson