Man Lands and Vedalken Shackles

[100miles&runnin]

what happens at the end of the turn when a factory goes back to being a non-creature when you have shackled it........

also, what happens to a creature that gets giant growthed to have it's power greater than the number of islands my opponents control

[Jaiminho]

You may choose not to untap Vedalken Shackles during your untap step.
{2}, {T}: Gain control of target creature with power less than or equal to the number of Islands you control as long as Vedalken Shackles remains tapped.

The condition for retaining control is that Shackles remains tapped. The rest is a bunch of conditions for assigning a legal target for this ability. This means that whether the creature is no longer a creature or has gained lots of power is irrelevant after it has resolved.

[cdr]

The "as long as" part is the condition for the Shackles's effect existing. Like Jaiminho said, the rest is just targeting restrictions and only relevant when the ability is being played and resolved.

[GGoober]

So after you've controlled the factory, and it reverts to a land, and during your next upkeep, if you untap shackles, Factory is returned to the opponent even though it is now a land?

[cdr]

It doesn't matter what it is, you still have to give it back.