Absolutely, a very useful FB application.

You’re two points are spot on:

1. Tweets that start with @replies are omitted from the Facebook status update, which is good because your contacts/ friends on Facebook are unlikely to always know who you are replying to and the context. However, You must START a Tweet with an @ reply to have it omitted from Facebook status updates. Thanks to Zack Beatty for the info on this topic: @ replies omitted from status updates.

For example,

“@ nredmond thx for the add” will update your FB status (due to the space between the @ symbol and the Twitter’s username).
“thx for the add @nredmond” will update your FB status.
“@nredmond thx for the add” will not update your FB status.

Also, it’s worth noting that Re-Tweets (for example, “RT @nredmond: New blog post up on the website”) will be updated to your FB status.

2. If you tweet a couple of times in rapid succession not all of your tweets will be updated to your Facebook status. From what I understand, Facebook only checks your Twitter updates every few minutes and some tweets can be lost. Furthermore, Facebook only allows a limited number (they don’t specify what that number is) of updates to your profile per day.

Two points worth noting – @replies don’t get published to your FB status, which is good. Also, if you tweet a couple of times in rapid succession, they won’t all update FB…