The following schema sum up HTML5 activities functional architecture.
Because it will force independence from Gtk/Python, HTML5 activities is a first step toward Sugar on Android.
The very first Web Activity is Wikipedia. Wikipedia is a Python activity embedding a WebView to display HTML Wikipedia pages. Searching and browsing is available from a standard Python toolbar. Clicking on a toolbar button change the current HTML viewed page or launch an history command (previous/next). To communicate from HTML to Python, Wikipedia embed an HTTP Server. When a hyperlink is clicked in the HTML page it call the HTTP server then run Python code.
HTML5 activities has been choose  as a feature for Sugar 0.100. HTML5 activities will be build on WebKit2 but if time permits we will implement compatibility with previous releases running WebKit1. HTML5 activities is accepted a project for Summer of Code/2013.
Some interesting discussion around this subject in the community:
- Sugar Web Architecture 
- Sugar Web UI 
- Localization 
- Renaming HTML --> Web 
- Running HTML5 activity on other platforms 
- How to deploy framework in the activity 
- Datastore API 
- Unit Testing 
- Webkit1/Webkit2 compatibility 
See TODO list of the project on .
GSoC Timeline progress
- Week 1: Working sugar-build environment, create a new activity 
- Week 2: Develop the RadioButton and CheckBox in Sugar HTML UI, sample here: , start a new Sugar HTML API
- Week 3: Start developing the Sugar Activity Palette
- Week 4: Working on DataStore handling to Activity Palette, solved issue on new Sugar HTML API
- Week 5: Publish a first blog post on its work, try to fix an issue regarding popup on home view
- Week 6: First mock-up and specification of the Markdown activity a Markdown format editor
- Week 7: First version of Markdown activity 
- Week 8-9-10: Object Chooser integration in the Markdown activity
- Week 13: Write a new version of Markdown activity, work on setting of preview metadata in webactivity
- Week 14: Publish the new version of Markdown activity, Final blog post