Nexus One users have begun receiving over-the-air (OTA) upgrades to Android 2.2, Google said yesterday.

The upgrade to Google’s Froyo platform allows users to turn the device into a portable hot spot and includes tethering and support for Adobe Flash. Google said at the unveiling of Android 2.2 in May that Froyo will be two to five times faster than past versions.

Users will receive a message on the Nexus One’s notification bar when they’re able to download the update. Google said the update will be rolled out “gradually” to phones and most users will receive the notification by the end of the week.

Google released the Froyo source code last week during the launch of the new Motorola Android-based Droid X with Verizon Wireless.

In a blog post about the Droid X announcement, Google Vice President of Engineering Andy Rubin said the search giant estimates 160,000 Android devices are activated every day. “The volume and variety of Android devices continues to exceed even our most optimistic expectations,” he said.