In a Spanish forum I've already reccommended some guys to stop trading OTC/Pinks and sub $1 stocks for a while until the witch hunt is over. Penson is the one leading the slaughter but it's likely that others follow 'cos the NSCC is behind this. The NSCC illiquid requirement is just plain nuts.
The NSCC illiquid rule has been implemented by Zecco by prohibiting online trading of sub $1 stocks if order size is > 25% 20-day average daily volume. It's way too much of a radical measure...as by definition it will cause a dead-end situation where if a stock has a period of small or no volume, the stock finally becomes untradeable as valid order sizes shrink down to zero. To add insult to injury, the formula to calculate the requirements is known by the NSCC and the clearing firms but brokerages don't actually know it. That way, brokerages can't know what to allow and what to block.
In my opinion the way to getting out of this mess is by reverse spliting the heck out of the OTC stocks then reducing A/S, so stocks get to trade at a $1 per share minimum.