I wore my same running shoes and running socks that I've been using this season (NB shoes purchased in Apr/May and PFit socks) and ended up with a purple 2nd toe from the Sauvie Island 1/2 Marathon on 07.04.10. Previously I've lost those toe nails before PTC from doing uphill/downhills and my toes jamming into the end of my shoes but didn't expect this on a FLAT course... with great gear. My previous runs 10 mi, 11 mi etc showed little to no distress to those toes.
Any ideas?

Usually when I have a blister or bruising issue, it's because I've changed something. I've experienced similar problems with no obvious changes. Change in temperature from what I'm used to, change in precipitation (the brief bit of rain during the 2008 Portland Marathon), even increased total weekly mileage (without any one run being particularly long) and change in pace have been factors. Have you kept a log of the number of miles on your shoes? Maybe it's time for a new pair?

Although you haven't found an answer yet, if you look hard enough, I bet you can figure out plausible reason.

Good luck!
Eric

How is the length of your toe nails?

When mine get a bit too long, I tend to have problems with a couple of toes. It's easier for that to happen in the summer when I'm wearing sandals most of the time. I've (mostly) formed a habit of checking them/rimming them on Wednesdays so they will be okay for a long run on the weekend.