I've joined the Ubuntu Font Family Interest Group and I'd like to provide feedback on the mono beta font, or, at least see if other people have reported the same issue I'm seeing.
What's the best way to engage with the ubuntu font folks?
SnapOverflow
If you are reporting a bug or problem with the font, you should file it in Launchpad. Otherwise, you could ask a question on this page.
Ubuntu Font Family had its own wiki page and there you can find that the project is hosted on launchpad for tracking bugs and wishes and there is also the Ubuntu typeface interest page on launchpad.