Version 3.0 supports multiple online galleries - from admin UI under custom -> gallery blogger can add multiple feeds and switch between them to install plugins from desirable source.
For BlogEngine.NET 3.0, default gallery feed is "http://dnbe.net/v01/nuget".
This feature can be helpful for organizations that want to restrict to specific list of packages or have developed their own for specific purposes, business, cultural and so on. BlogEngine supports feed provided by standard NuGet package (NuGet.Server) that can be installed to any ASP.NET application and be exposed as gallery source (hosting your own NuGet feeds).
Another reason for this feature was to be able move to "native" BE gallery site that can be easily maintained by BE team, unlike currently used 3rd party that is hard to maintain and impossible to upgrade..