Working with FF3.5.5 and JP0.6, I developed an add-on. It worked nicely, but when I installed the add-on, rather than developed it in the about:jetpack tab, it started crashing the browser each time I started it. Only disabling JP0.6 alleviated the problem. 0.6.1 did not fix this issue.
5 stars for the add-on, -1 star for crashing the browser.