If you don’t know about OTR, it’s awesome. It lets you have end-to-end encrypted chat sessions with people so that only you and the person you’re chatting with can read the chat messages and all other parties—such as your chat server (often Google), your ISP, or anyone else eavesdropping on your—cannot. It also has cool features like forward secrecy that other cryptosystems like PGP don’t have. If you’ve ever been to a CryptoParty, setting up Pidgin and OTR and learning how to verify keys is always on the schedule.
About a month ago I decided to rent a $16/month VPS from Gandi, hosted in Paris, that I’ve been using to run a fast Tor exit node called gollum. I wanted to tunnel my Thunderbird, Pidgin, and IRC traffic through gollum as well, but realized that that wasn’t a good idea. Tor recommends that you don’t mix personal traffic with exit traffic, not to mention freenode and other IRC networks block Tor exits.
Each time your computer makes a connection to a server on the internet, you tell the remote server, as well as your ISP and every router in between, your IP address. If you’re using the internet on your phone you might be disclosing the IP of your 3G or 4G connection, or the IP of the wifi network you’re connected to.
If your phone checks for new emails or tweets every couple minutes, or keeps up a consistent connection to your instant messenger server, any of those services is almost definitely logging a history of your IP addresses.