I realize that this is a contentious issue right now in running circles, but are there any other barefoot/minimalist runners out there? I use my Vibram Fivefingers whenever I run and love it. So much better than when I used to run in shoes.
And as a side note, I will be borrowing a bike to train on and use for my first tri, and since it has the option of both clip-in and regular pedals, I'll be going with the regular (I own no clip shoes). Any thoughts on riding with the Fivefingers?

Your feet are your feet. Wear whatever you feel comfortable wearing. I ride with cycling shoes, Five Fingers and sport shoes depending on what bike I am riding, what I am doing and where I am going. Cycling with Five Fingers and sport shoes is mediocre because I don't get the correct positioning and always have to adjust my footing which can be annoying. I am a big fan of clipless pedals and cycling shoes because I just get, go and don't have to worry about my positioning.

I prefer to do my barefoot running while I'm actually barefoot. If you've already been using the fivefingers and working on a proper foot strike you may enjoy it more than you'd expect. Try wrapping something soft (sheepskin comes to mind) around some cheap platform pedals and go barefoot. Just watch your speed when you put your feet down.

I've been using FiveFingers too, and love them. I never ran much in running shoes, so can't really compare the two. I used to use the fivefingers on the bike for casual and training rides. Ventilation seemed to be the nice feature of fivefingers on the bike. I decided clipless was a better choice for me, though. With the right shoe, you can get almost the same ventilation, and I like the other advantages of clipless.

The main advantage of proper bike shoes is power transfer to the pedal. The sole of the shoe is rigid, allowing for maximum power transfer. Shoes for running or other activities will have flexible soles, which will lead to power loss, and thus slower possible times on the bike. I can only imagine that the sole of the fivefinger is even less rigid.

The big thing about barefoot running is learning proper technique. If you have proper technique, (or are working on proper technique), there is no reason to not protect yourself from injury.

So, no, I'm not a minimalist runner. I'll take the advice of my coach who seems to know what he's talking about...

For your first triathlon, whatever you have is fine, cycling shoes will be better, but not necessary to complete a triathlon. I have my own opinions about running with five fingers, but for your first triathlon, you could literally wear clown shoes or wingtips even and still finish it.

Yes, the fivefinger sole is completely flexible.

I've always wondered about this 'main advantage of proper bike shoes', though. The same theory applies to running shoes, thus the arch support and generally rigid form. There's some evidence it's not accurate and that the arch of the foot transfers force wonderfully. That, in fact, is part of the reasoning behind FiveFingers. I'm not trying to be controversial, and I don't use FiveFingers on the bike currently, but I've always been suspicious that the rigid sole isn't magically better. I know clipless offers other advantages too of course, just musing about this bike-shop piece of wisdom. (edit) I've used fivefingers for about 400 miles, thus my thoughts. On the other hand, I don't do long distances at the moment, or bike races, which may completely disqualify my observations!

You can be skeptical, but the fact remains true that rigid soles provide better power transfer. When running, your heel springs up and down in relation to the ball of your foot. When pedaling, the heel doesn't spring up and down but remains in constant relation to the ball of the foot. As firm as you could hold your foot, it will still have more flex than a rigid shoe sole, and thus more power loss.

WRT the virtues of bike shoes - just remember that cycling is not creating the impact running does. Cycling is a not a weight-bearing sport. The shoe is there for powertransfer as much as anything. Having shoes that fit well and are set up with the bike to keep your knees & hips in line is quite important - especially if you do a lot of miles. Running (barefoot/five-fingered or shod) is a different sport and has completely different issues.

I was a sprinter in my youth and am now able to use the form and technique I learned then ( although modified for distances) to help me cope with an increasingly tired body. I think there is something in the barefoot philosphy although i do most of mine on the beach and wear shoes ( newtons) on the road. Running barefoot can definitely help you be more aware of how you are using your feet and therefore, develop better technique but for a long race, I still prefer shoes. Having said that, its shoes that are on the "racing flats" end of the spectrum that I use.