When I watched
Google Developer Day US – Better AJAX Apps:Gears, GWT, Dojo
I saw how AJAX applications developed with the Google Web ToolKit could be interfaced into the Google Gears browser plug-in so that it can run off-line. The service can run even when one is disconnected and then when (re) connected the local state and the server state are synchronised. As presented in
http://code.google.com/events/developerday/mv-sessions.html#building_better_ajax_apps
there are several situations where people want to run web applications even when not connected. And one can run off-line the same way (even using the same URLs) as one does when connected.
The combination of GWT and Gears may provide us tools for doing this.
Modelling4All: Learning through composing computer models. 
Peter Miller said
I haven’t done any of this but it might be worth bearing in mind that Adobe Air and MS Silverlight are in the same general ballpark (I think). If what you doing is mainly text-based, it might be worth considering TiddlyWiki.
modelling4all said
We should look closely at Adobe Air, MS Silverlight, and Sun’s JavaFX as alternatives to Google’s Web Toolkit (GWT). My initial experience with GWT has been very positive. I like the idea of debugging as any other Java application and then automatically turning it into a web service. Note also that Adobe Air and MS Silverlight are proprietary systems unlike GWT and JavaFX which are open source.
modelling4all said
Regarding wikis we will be hosting one but this isn’t the main focus of the project. TiddlyWiki looks interesting but the idea here is to “have our cake and eat it too” in that we want the advantages of being server based (saving, sharing, no installation, etc.) but also have a means for those who want to use our software without always having a net connection to have a way to do so. Google Gears seems to offer a way to do both.
Peter Miller said
There are actually quite a few different server-based implementations of TiddlyWiki now, the best known probably being tiddlyspot. However, I take your point.