These forums are full of threads started by people who are angry that the Roku3 was only released a week after it was announced (they wanted more time).
I thought that the announce date (March 5th, the PR
is dated the 6th, though there was a Roku blog post
on the 5th) was the actual ship date--it could be ordered from Roku or Amazon when the info went live on their website. I ordered mine from Amazon on March 6th and would have ordered it on the 5th but couldn't find the listing on Amazon (if you searched for Roku 3 it was 3 pages deep in the results
); with Prime shipping I got it on the 8th.
I salute them for announcing that the new UI would be rolling out to the 2nd gen boxes at the same time they announced the Roku 3; they might have sold more Roku 3s if people thought that it was the only way they were getting the new interface