Some arts I have trained in state that when you see "splotchy" red dots on the palms, that is ki manifesting itself (I have no opinion one way or the other and yield to those with greater expereince, at the very least I assume its more circulation). If you engage in some of the stuff talked about in the non-aikido forum, it may happen, but I can't state wether or not I expressed more "correct" movement or not when it occured.
I assume that is what the original poster was referring to.
As for moving with the center, you will probably get better discussion out of the non-aikido forum as well for specific exercises.
For whatever it may be worth, after I began training seriously (when I did such a thing) I experienced this (or something similar, at any rate). The first time I noticed this I thought I was bleeding from my pores, but it wouldn't wipe away. I just chalked it up to increased circulation...which is, I believe, an example/attribute of increased ki flow, right?
Also, I remember being told my first day of class that I should consider the feeling of pushing a shopping cart while getting groceries; which resonates with the phrase, "when one thing moves, everything moves," and suggests to me something about how one might begin to approach moving from center, making the arms extentions of it instead of pushing with arm strength.