Fixed issue that locally declared SurfaceControllers are routed through 'umbraco' area, this should not have been the case.

Created new CacheHelper which replaces the old Cache class and is accessible via the UmbracoContext.
Added new CachedPartial extension method to be able to cache the output of your partials (also by page and by member)
Added mew CacheHelperApplicationEventListener in order to automatically clear the partials cache when content is published, media or members is saved.

src/Umbraco.Web/CacheHelperExtensions.cs

@@ -0,0 +1,95 @@
+using System;
+using System.Web;
+using System.Web.Caching;
+using System.Web.Mvc;
+using System.Web.Mvc.Html;
+using Umbraco.Core;
+using umbraco.cms.businesslogic;
+using umbraco.cms.businesslogic.web;
+
+namespace Umbraco.Web
+{
+
+	/// <summary>
+	/// Extension methods for the cache helper
+	/// </summary>
+	internal static class CacheHelperExtensions
+	{
+
+		/// <summary>
+		/// Application event handler to bind to events to clear the cache for the cache helper extensions
+		/// </summary>
+		/// <remarks>
+		/// This would be better left internal, however
+		/// </remarks>
+		public sealed class CacheHelperApplicationEventListener : IApplicationEventHandler
+		{
+			public void OnApplicationInitialized(UmbracoApplication httpApplication, ApplicationContext applicationContext)
+			{
+				if (ApplicationContext.Current != null)
+				{
+					//bind to events to clear the cache, after publish, after media save and after member save
+
+					Document.AfterPublish
+						+= (sender, args) =>
+						   ApplicationContext.Current.ApplicationCache.ClearPartialViewCache();
+
+					global::umbraco.cms.businesslogic.media.Media.AfterSave
+						+= (sender, args) =>
+						   ApplicationContext.Current.ApplicationCache.ClearPartialViewCache();
+
+					global::umbraco.cms.businesslogic.member.Member.AfterSave
+						+= (sender, args) =>
+						   ApplicationContext.Current.ApplicationCache.ClearPartialViewCache();
+				}
+			}
+
+			public void OnApplicationStarting(UmbracoApplication httpApplication, ApplicationContext applicationContext)
+			{
+			}
+
+			public void OnApplicationStarted(UmbracoApplication httpApplication, ApplicationContext applicationContext)
+			{
+			}
+		}
+
+		public const string PartialViewCacheKey = "Umbraco.Web.PartialViewCacheKey";
+
+		/// <summary>
+		/// Outputs and caches a partial view in MVC
+		/// </summary>
+		/// <param name="cacheHelper"></param>
+		/// <param name="htmlHelper"></param>
+		/// <param name="partialViewName"></param>
+		/// <param name="model"></param>
+		/// <param name="cacheMilliseconds"></param>
+		/// <param name="cacheKey">used to cache the partial view, this key could change if it is cached by page or by member</param>
+		/// <param name="viewData"></param>
+		/// <returns></returns>
+		public static IHtmlString CachedPartialView(
+			this CacheHelper cacheHelper,
+			HtmlHelper htmlHelper,
+			string partialViewName,
+			object model,
+			int cacheMilliseconds,
+			string cacheKey,
+			ViewDataDictionary viewData = null)
+		{
+			return cacheHelper.GetCacheItem(
+				PartialViewCacheKey + cacheKey,
+				CacheItemPriority.NotRemovable, //not removable, the same as macros (apparently issue #27610)
+				null,
+				new TimeSpan(0, 0, 0, 0, cacheMilliseconds),
+				() => htmlHelper.Partial(partialViewName, model, viewData));
+		}
+
+		/// <summary>
+		/// Clears the cache for partial views
+		/// </summary>
+		/// <param name="cacheHelper"></param>
+		public static void ClearPartialViewCache(this CacheHelper cacheHelper)
+		{
+			cacheHelper.ClearCacheByKeySearch(PartialViewCacheKey);
+		}
+	}
+}