I'll definitely bring up the question about iron with the pediatrician next time I see him. I suspect, though, that 'mother nature' somehow found a way to supply all the needed nutrients to babies otherwise we wouldn't all be around. ;-)
I think that most of us were started on solids way before 4-6 months. Obviously, research has now shown that's not best, but it's not that we all survived soley on breastmilk for the first year.
The site that you posted, sharon, has some information that conflicts with a lot of what I know. Such as giving cow's milk starting at 6 months if necessary. I know that a big reason for not giving cow's milk is that it doesn't have all the nutrients a baby needs, but it can also be pretty hard on their digestive systems, especially at 6 months I would think!
6. The breastfed baby 4 months of age needs to be getting more iron than can be provided by breastmilk alone.
Not true. For the baby the baby born at term who is breastfeeding exclusively, all the iron required is provided by breastmilk. However, by 6 months of age, more or less, it is prudent for the baby to begin getting more iron than that provided by breastmilk alone.
It goes on to say that infant cereal may not be the best way to get that iron, which is fine. There are definitely a lot of other ways, the important thing is that babies do need that iron at some point, and won't really be able to get it from breastmilk indefinitely.