We are currently designing a GIS intranet application using GWT and ESRI ArcGIS. We are looking at 2 client side Javascript libraries:
The library will have to support fused and non fused map caching as well as some layers that are dynamic. Open Layers GWT integration exists but the ESRI library is based on Dojo.
I'm looking for information and advice on where the gotchas will be for either approach.
I'd probably go with Dojo as ESRI is already built on that one. It has great way of creating widgets and relatively good documentation. a lot of can be found at their forums (though these are now closed for posting new questions -> use stackoverflow instead or their mailing list)
here is the link that might be helpful to you
javascript libraries comparison
If you're already using ArcGIS, go with the ArcGIS API for JavaScript. I think there are a lot more people out there using ArcGIS Server fused/non-fused map caches + ArcGIS API for JS than ArcGIS Server + OpenLayers so you'll have an easier time finding samples that are applicable to what you're doing.
GWT is perfect to structure big one-page application. So I'm developing a wrapper for the Javascript library.
http://github.com/lukefx/EsriGwt
It's in a super early state...I'm searching for someone who wants to help me :)