Has Pressflow 6 been discontinued?
There are a few questions here:

What was the timeline of events for the 6.30 release of core and Pressflow?


Core security release on January 15th, 2014 which had been in the works for a few days beforehand and the Pressflow maintainers are welcome to participate in that process to help them review the patch and be able to apply it quickly
January 15th, 2014: Some commits and pull request for Pressflow 6 to incorporate that change
January 21: a merge commit merging in that pull request and probably making the tag


Why isn't there news about Pressflow 6?

Well, it depends on where you want to go to get news and what your expectation is. Drupal 6 and Pressflow 6 are pretty slow in terms of news. They are stable except for these security updates. I think it's reasonable that the promotion/updates about it are minimal beyond what is necessary for development. If you want to know what's going on (including the sate of the last release) check the issues and pull requests. And if you went there on January 15th you'd see a pull request that you could try out to get the security update and help in the process of releasing the next version by providing a review.

Will there be timely updates moving forward?

Peter Wolanin (and Gabor Hojtsy, I'm told) are now able to commit changes to the Pressflow repository on github. It seems likely that they are interested in Pressflow because many of the users of Pressflow are clients of Acquias. Peter and Gabor are both Security Team members (and Gabor a D6 maintainer) who stay aware of the core security releases. So, I think it's safe to say that updates will flow more quickly in the future.