Many people (including me) are disappointed that Twitter recently cut off API access to LinkedIn. Luckily, I have found a way to still selectively tweet to LinkedIn using the #li hashtag. You will know from my previous post that pushing all of your tweets to LinkedIn is annoying. In fact, it could upset a potential new employer or client. Never send all of your tweets to LinkedIn.
If you prefer to use the #in hashtag you can use Adam's IFITTT.