We're a team of a dozen or so software engineers (many ex-Google and YC) who've been working on fixing Healthcare.gov for the future, since December. We're actively looking for experienced software engineers. Several have joined in the past few months.
(If you've seen this comment before, we were looking, but now we're very-much looking.)
The external environment may be frustrating compared to what we're all used to, but internally and day-to-day we're running like a startup-- github/node/backbone/AWS/asana/standups/etc. We're finally shipping and we're going to keep shipping.
Change starts with a small group of thoughtful, committed software engineers (...paraphrasing...) and there are many groups now seeding different parts of the system; our area is Healthcare.gov and associated systems. Because we began in a crisis situation, and other unique factors, some of the usual downsides mentioned in this thread don't apply to us.
Email us! We can also refer you to the other groups referenced in the OP if they make more sense for you.