This one:
http://aurora2.pentarch.org/index.php/topic,1680.0.htmlIs the big master thread but that's from a while back, now. Not sure if there's been a change recently.
But I do know that it's not 10,000 km/s bonus, certainly. I was doing some testing with a 14k km/s ship trying to board a freighter at about 2.5km/s, and I was losing over 60% every time. With the formula from that, that'd mean I was losing 20-(14k/2.5k)xD10, so 20-5.6xD10, or 14.4% to 144% which "feels" about right. Didn't do exhaustive testing, but I was losing over 50% quite often with the occasional total destruction.
I suppose that formula would also mean that a 10x speed bonus would give you a 10% to 100% range, so you'd have a basically 0 chance of NOBODY landing. But still, I'd say that a 10x speed bonus is the bare minimum unless you have a lot of extra Marines around you don't much care about.