New rules for Tier 1 and Tier 2 were introduced in December 2012. Previously, people who had worked on a Tier 2 visa whose visa expired would have to wait a year from the visa expiry date until they could reapply. The new rules allow them to return one year from when they left UK, not when the UK visa expired. The visa is valid for up to 3 years. This means, if they leave earlier they may return earlier than they would have previously been able to.
Also, workers on Tier 2 (Intra Company Transfer) visas earning more than £150,000 can now stay for a maximum of nine years, instead of just five years.