I used to do 5-6 miles at lunch on most days.... well up until I got me a colbalt chromium hip 

I do it on occasion.  More so in the winter when some mornings can be too cold for me.  I don't like it so much, though.  Coming back all sweaty, showering, squeezing in the actual eating of lunch.  It's a drag.  Not to mention that some days I plan to run but work gets so busy that it just never happens.

I did last year and the year before. It was a really nice break in the middle of the day, and way better than running in the dark. You should totally do it. 

luckily, there is shower at work and a boss who does not know when I am gone.  I've done 16 mile runs during "lunch".  The Male Pattern Baldness helps with the post-run hair issue.

A new lifetime fitness gym has opened very close to me.  So I'm contemplating using them for my lunch workouts.  I can take 1 and 1/2 hour lunch breaks due to my work schedule so I don't have an issue of having to really hurry.

I've avoided lunch time workouts at LA Fitness because I don't like their showers and always feel like an exhibitionist.  But the showers at Lifetime have glass doors and and are somewhat more discreet.  Plus Lifetime furnished towels so I'm contemplating it.  I think I can get 6 to 7 miles in outside or on the treadmills during inclement weather.

My job is fairly flexible (a lot of my co-workers frequently work from home, in fact), so I'm not stuck with trying to get my runs in during a narrow window of time. We also have a shower in the office so post-run clean up is no problem. (Well ... except for the fact that the cleaning lady can't hear the shower running ....) We also have a nice 5k loop around the complex with options for shorter cut-offs. As a result, most of my weekday runs are at the office at lunch.

  The lack of shower facilities doesn't have to be a major problem. Take a wash cloth with you, dampen it, and wipe down. That should get you through the afternoon without offending too many people. (Of course, doing this will be awkward enough.) The hair might be a bigger problem, though. Maybe find a 'free' style that doesn't show run effects. (For me there's no problem - I don't do a lot with my hair when I don't run.