As Monica has already pointed out, the information on Area 51 is woefully out of date. (Great phrasing, so I'm borrowing it.)
When could we hope to see this site released?
The site is already released. It's here, there's activity (plenty of it!), and more than one of the higher-ups seem to feel that we are taking on a difficult type of subject matter and handling it well. I would consider the risk, at present, of the site being shut down to be very small.
What could perhaps cause the site to not eventually graduate from beta would be if there is a marked deterioration in the quality of content posted, or if the site's scope turns out to broaden considerably. I do not believe we are seeing the latter (questions are being closed for various and from what I see appropriate reasons, and what's more, they are being closed by community voting rather than by the infamous mod-hammer), and my personal feeling is that while some posts, particularly questions, turn out needing work beyond the first revision, the community appears to be guiding newcomers which is almost certainly a huge plus in the eyes of the people with the keys. In general a few (1-3) questions are closed per day out of the 5-15 or so questions posted per day; consider that some of these are reopened later, and that is not a bad fraction at all.
A few things that we do have (almost certainly an incomplete list):
- High quality content
- Lots of activity compared to many other sites
- Lots of community decision-making, including voting on posts and closing/reopening questions
- A very active Meta site
- An active chat room
- A generally welcoming atmosphere where more experienced community members guide people who are new to the site and/or the Stack Exchange format in general
- An increase in new content added; currently questions are trending marginally upwards, and answers are practically taking to the skies and are currently close to the site's all-time high since the public beta began. Upvotes are trending upwards while downvotes are holding relatively steady and starting to trend upwards at a much lower level.
All of these are great signs going forward, but the fact that the site is able to generally keep producing high-quality content (as also indicated by the voting pattern shown by the community at large) is a stellar sign in my book at least.
Which pretty much brings me to the bottom line. Keep up the good work. Try to bring new people into the fold. Post links to great questions and/or answers elsewhere on the Internet. Keep mentoring new users (remember that we are all new to this at some point). Keep contributing. Keep voting, both up and down as appropriate. It's a great sign in a way that question votes are not very far below answer votes; around a quarter of all up and down votes are on questions.
TL;DR: Let's prove with every action that this site is worthy of graduating, and eventually it will graduate. Until then, let's obsess more about ensuring that it will eventually graduate than about exactly when it will.