I managed to create a partial workaround by editing twitter-tools/twitter-tools.php so that the following line…
define('AKTT_API_USER_TIMELINE', 'https://twitter.com/statuses/user_timeline.json');
…now reads:
define('AKTT_API_USER_TIMELINE', 'https://api.twitter.com/1/statuses/user_timeline.json?include_rts=true');
This causes “new retweets,” or “newfangled retweets” as I like to call them (also known as “native retweets,” I guess), to post like all other tweets. HOWEVER, they have the same limitation as newfangled RTs in the Twitter RSS feed — they are truncated after 140 characters if the retweeted tweet is long enough that adding “RT @originaluser” before the tweet causes it to exceed 140. Ugh! Among other things, this makes it pointless for displaying RTs of long-ish tweets that have links at the end, since you lose part of the URL.
I can’t figure out why this is happening — I know it’s *possible* to avoid it, because when you import new RTs into FriendFeed, it doesn’t happen — or how to fix it. Any ideas?