Been aching to try some of the bigger improvements from Windows 10's Anniversary Update? It's time to give them a shot. Microsoft has released a Windows 10 Insider Preview (only available on the Fast ring) that includes a few of the choicer improvements. The highlight is likely to be the Cortana-based cross-device features: if you have an Android or Windows phone, Cortana will tell you when your handset's battery is running low, help you find a lost phone and share navigation directions across devices.