I saw a couple threads on the web and just saw this from a US carrier:
A T-Mobile spokesperson also confirmed the delay: "We can confirm we have received stock of the white variant of the handset and expect to be able to fulfil all the pre-orders we've received for this device at launch.
"However, we've been advised by the manufacturer of a shipping delay on the pebble blue version.
"Although we expect to receive stock shortly, we are contacting customers who have pre-ordered this colour to let them know that there may be a slight delay, and to reassure them we will look to fulfil their order as swiftly as possible."
A T-Mobile spokesperson also confirmed the delay: "We can confirm we have received stock of the white variant of the handset and expect to be able to fulfil all the pre-orders we've received for this device at launch.
"However, we've been advised by the manufacturer of a shipping delay on the pebble blue version.
"Although we expect to receive stock shortly, we are contacting customers who have pre-ordered this colour to let them know that there may be a slight delay, and to reassure them we will look to fulfil their order as swiftly as possible."