Series 4 at TRU
Cygnet has reported at his Ugly Duckling blog that TRU branches in the USA now have series 4 on the shelves.
He says: 'If you're in the US...Call 1-800-869-7787 , Press menu options 1, 3, and then 2. Ask the operator to check the availability of item 578074"
You can keep track of the global rollout and add your own sightings on his rollout map.
Update: Doh! I've just read on his blog that he got this information from comments made today to a news article here at Brickset. I really shoud pay more attention to my own site! There's links to pictures of the dots in the comments, too.
Update 2: I've taken a snapshot of his U.S. rollout map (as of 3/17/11) and pasted it above for quick reference (YC)
Update 3: They have hit the East Coast (3/22/11)