You are right, I forgot to include the files /Admin/PageSettingsSaved.ashx and /Admin/PageSettingsSaved.ashx.cs to the MonoDevelop project. I have fixed this in svn trunk. I will be making a new release within the next 2 weeks so I will have this fixed in the new release. I'm surprized no-one has reported this before.
If you branch down the mojoPortal.Web project then right click the Admin folder and choose Add Files, then browse and add those 2 files then rebuild it should work using the mojoportal.mds (but not the mojoportal.mono.sln)
It works for me using the Mono 188.8.131.52 VMWare image and using mojoPortal from svn trunk. I don't know about any issue with Mono.Web.Util, it does not happen for me.
Note that the svn trunk version is pre-configured for Sqlite (because its zero configuration needed) whereas previously it was pre-configured for pgsql. You can change the references from the Business projects to the data projects for pgsql manually if you want to use pgsql.
Hope it helps,