I use posterous.com to post all my updates across all of my streams (blogs, twitter, facebook, friendfeed, etc...). The only exception to this is the occasionally semi-private posts in facebook. This has worked extremely well and has simplified the process tremendously for me. But recently I find myself wanting to use newer features that are not directly supported by posterous. Retweeting is one of them. To be clear, posterous allows you to retweet anything in posterous (using the old "RT" standard), but there is no direct support for the new Twitter retweet feature in posterous as shown below.
So I use other tools, and this retweet doesn't cross into my other streams (Facebook, Posterous) automatically. Re-tweet is an example of a drawback of these types of services (i.e. posterous). Does it become an escalating arms war of features. As services add features, can posterous keep up and normalize these features across all streams effectively? I hope so.