Associated Press reports the TSA has delayed the change in policy to assess feedback from the Aviation Security Advisory Committee. It also appears to have been a very sudden change of heart: last week, a TSA spokesperson insisted that the Boston bombing wouldn't affect the new rules, as Verge points out.
The policy certainly drew its fair share of criticism when it was announced last month, with tthe he Flight Attendants Union Coalition going as far as saying the rules are "poor and shortsighted". And regardless of where you stand on the idea of knives aboard planes, it does seem faintly ridiculous that water should remain banned.
There's currently no new date set for when the policy will finally rollout. [AP via Verge]
TSA Delays Its New Knives-on-Planes Policy