I think these last posts are actually quite relevant to your question. Although it seems to go a little off-topic the central issue is still, whether or not Fe(II) will be formed in acidic solutions.
One way to look at your question is based on pourbaix diagrams, the wikipedia page on this shows an example of the iron system. It shows that without complexing agents Fe(II) is stable in acid under 'regular' conditions, but as Borek already pointed out, the presence of oxygen can interfere, since it will lead to a more oxidising environment. http://en.wikipedia.org/wiki/Pourbaix_diagram
You can also stabilise oxidation states using complexing agents, compare for example Fe(III)/Fe(II) (0.771V) to [Fe(CN6
(0.358V). In this case you're not dealing with just 'aquated' iron ions anymore though, but with complexes.