Twitter has joined Facebook and a few other sites in offering a higher level of security for users. Twitter users can now opt for https setting on their accounts, which will encrypt everything going through an open wireless connection (like you might find in a library or cafÃ©). The company says that it hopes to make Twitter the default setting soon. The setting does not follow your account from web to mobile but they're working on that as well. A lot of companies are being asked to switch to https. It's a lot more complicated and a lot more work for engineers running the site and it does slow your web experience down, although it's not so much that you would even notice it. The recent publicly available Firesheep extension lets you eavesdrop on any non-https web session from a public network. The ease/creepiness of that probably fueled Twitter's conversion.