This is a Community Server wrapper for the XStandard text editor control. Community Server uses a provider model that allows users to easily change which text editor they want to use, as long as there is an appropriate wrapper for it that implements the ITextEditor interface. For more information about the XStandard text editor, visit the XStandard web site at xstandard.com
See Kevin Harder's blog for more details.
Update [Jan 5, 2006]: The XStandard Wrapper has been updated with a couple minor fixes. It will now behave properly when multiple editors exist on the same page (instead of the values being joined together with commas) and will degrade nicely to a plain textarea if the users browser does not support the XStandard ActiveX control or Mozilla/Firefox plugin (or chooses not to install it). Also, line numbers were removed from HTML (XML) view and it will automatically clean up invalid HTML that was pasted in instead of prompting.