Cherry is a chrome OS mod released by Hexxeh, a Chrome OS developer. The cherry OS has many advantages over the default Chrome OS. It has a small size of 300 MB. Not only this, it fits into a USB drive of size 1 GB unlike the original build, which requires at least a 4 GB USB drive.
In addition to that, it now includes out of the box support for Wi-Fi. Wi-Fi was initially unavailable on Chrome OS and is still unavailable. It can be enabled by copying the Wi-Fi firmware from your default Ubuntu or Ubuntu based installation, to a folder in the Chrome OS USB-drive. All that trouble has been done away with in the Cherry build of the Chrome OS.
The OS can be tried on any netbook, laptop or desktop. It is available as an image file that can be written to a USB drive using an appropriate tool. Windows users can refer to this page for help on making a bootable Chrome OS image. The default username and password for Cherry OS is facepunch.
There are three download links on this page. One is a torrent download, others are HTTP links. The download is absolutely free. As the homepage says, you can report any bugs to @Hexxeh on twitter.
Chrome OS being Ubuntu based, is highly customizable and is fast developing. This parallel build of Chrome OS is a big hit and Wi-Fi support appearing on it even before on the Chrome OS itself is a positive response from the open source community on Chrome OS.