First, run rake in both edge Streamlined and the Sports sample app. If something breaks, stop and fix it first. Otherwise:

Second we tag our current release from edge, following the convention of rel_x_y_z. Assume all these commands are run from streamlined root.

    svn cp edge/ tags/rel_0_9_0
    svn ci -m "Tagging release 0.9.0"

Now we delete the latest stable branch, and recopy it from the latest stable tag we just made.

    svn del branches/stable
    svn ci -m 'prep for 0_9_0 release'
    svn cp tags/rel_0_9_0 branches/stable
    svn ci -m 'and copy latest stable to the stable branch'

Now post the announcement to the Streamlined general list, the Streamlined core list, the General Rails list, and even Ruby talk if you're feeling frisky. An announcement on the blog is also a good idea.