Both my FF3.5 and IE7 show submit hugging the bottom text input in Newsletter and Request a Call Back. It would help if the forms were valid (did you know a form must have a block element as a direct child? Usually a fieldset but even a div or a p would make it valid), but I think what you'll want is instead a bottom margin on the last non-submit input.
That can be hard without adding classes to things, but bottom margins are usually safer than top margins, because top margins can slide up behind (or over) the elements above. Bottom margins though are usually pretty straightforward.
So the select and the text input in the newsletter, if they had bottom margins, that would work... complicating this is the table (why??) in Request a Call...
And, of course, I need to say that the text above the inputs are labels, and ideally should be marked up as such... : )