ArcGIS Server 9.3.1 and JavaScript API 2.3

[GadyPitaru]

Can I use version 2.3 of the JavaScript API (specifically the compact build) to consume map services served out using ArcGIS Server 9.3.1?

[derekswingley1]

Yes, the JS API is backward compatible. The only caveat is that you cannot use JS API features that aren't supported by the release of ArcGIS Server you're using. For instance, you would be able to do any editing against your services. If you're just displaying and querying, you should be good to go.

I posted earlier this week about creating a Feature Layer using v2.3 of the JS API and a 9.31 service:  http://forums.arcgis.com/threads/32424-Attribute-field-names?p=109561#post109561