I am not sure what took so long, being that Google+ is so important to Google. The Google Webmasters team finally made their own page on Google+ at +GoogleWebmasters and announced it on Google+.
They had a Twitter account for years at @googlewmc and now playing catch up on social media, adding their own on Google+.
Don't get me wrong, many Googlers on the webmaster team are very active on Google+. Just not on the official Google channel, now they can be.
Last night, Google announced it on Google+ saying:
Welcome to our Google+ page!The webmaster outreach team at Google will use this page to post announcements, events, tips, quizzes and other resources to help webmasters like you make great sites that can be found in Google Search. Follow us and join the webmaster community!
They then posted this picture:
I wonder if they will keep it up? I assume the Matt Cutts videos will be posted here frequently, as they are on Twitter.
Forum discussion at Google+.