I wrote the "new beta feature" line with the future tense, to match the recurring "The new version of MediaWiki will be on [...]" item above. This seemed logical to me, because when the message is delivered on Monday the feature will not yet be available, but will become available during the week (Tuesday/Wednesday/Thursday) as the deployments roll out to each group of wikis. I think that is the intended use of that section, but possibly I've misunderstood?
Hmmm, I've now looked through the last few issues, and I see a slight mix of present and future tense in the "Changes this week" section (e.g #34 says "You can soon watch when something is added to or removed from a category"), but mostly present tense. I agree this is worth clarifying/standardizing in future issues.
HTH, Quiddity