Twitter is working to cater to new users and make it easier for them to get started with the service with an instant timeline feature. Instead of requiring new users to go out and follow Twitter users on their own, the instant timeline feature brings in content without going through the traditional setup process.
After Twitter scans your contacts in the signup phase, it will automatically present new Twitter users tweets based on who their contacts are and who they follow on Twitter. Essentially, Twitter is guessing which accounts and topics might interest you.