I just talked to the people at Echo, they are using the new ISLD rates, they say their website should reflect that later today. I think they had just forgotten to update the site from the way it sounded.
Basically, if you traditionally put bids and offers on ISLD, not buying into or above the ask or selling at or below the bid, then you are adding liquidity. When you add liquidity, you receive a rebate of $0.0011 (.11 cents) per share. This rebate is INSTEAD of paying the $0.0019 ECN fee. It does not mean that you pay the fee, then get some back.
What that means for traders is that if you traditionally are putting bids and offers on ISLD, it is possible to never pay an ECN fee and only receive ISLD rebates, thus effectively lowering your per share costs with Echo by over a tenth of a cent per share. Since their rates are so low anyways, for guys that use ISLD a lot this beats anyone I know of.