I have been waiting for the new version (V3) for a long time. This new version has a superb feature that called Cloud Services. This is the killer feature of Arc2Earth V3 due to decrease the need of ArcGIS Server. It uses Google App Engine for hosting and storage. This gives scalability to your GIS services.
Thanks to Brian, last year, I had a chance to try the clouding services for my presentation about Cloud Computing. I just changed my ArcGIS Server URLs to App Engine URLs and it was still working. There is no need to do extra things to work with Cloud Services, because it is fully compatible with ArcGIS APIs.
Anyway, I’ll write in details later when I finished reviewing the new version.