Token transferability was enabled, exactly at block number 1,205,128 on August 18th at 16:39 UTC. This will not change the denomination of DOT (old) which still represents 10**12 Planck.
The redenomination will occur approximately 3 days later, at around 16:40 UTC on the 21st August, exactly at block number 1,248,328 where each New DOT will represent 10**10 Planck, 100 times less of an amount.
Do not be fooled by suspiciously low DOT prices. Though most exchanges will represent DOT accurately, there is a chance that some unscrupulous exchanges may choose to enact the redenomination prior to the date agreed by the Polkadot community, and thus report the apparent price at approximately 100 times lower than the actual market price.
We believe such action is irresponsible, possibly constituting fraud through deceptive advertising and certainly puts Polkadot stakeholders at risk. As a responsible member of the Polkadot ecosystem, Web3 Foundation will make such a proposition as unattractive as possible, however, since Polkadot is now decentralized and permissionless, and since this change is a purely off-chain "visual" alteration, we can do little against a determined and centralized off-chain service abusing the trust of their users. As always, we urge the Polkadot community to be careful, vigilant, and communicative.
See the Polkadot blog post for more information.