After several attempts to make mojoPortal run on an Ubuntu Hardy machine (Apache/2.2.8, Mono 2.0.1 and MySql 5.0.51a), I've found a final workaraound and made it work.

The server was already running a couple of PHP5 applications, so I followed this howto (note: setting prefix /usr/local leads to a lot of problems, so use prefix=/usr in all compilations) to allow Apache2 run both XSP2 and PHP5. Using default packages would uninstall one or the other due to incompatibilities. I downloaded and compiled latest stable Mono and Mod_Mono source tarballs: 2.01

XSP2 now were running ok the test pages, under Apache2, but I smashed against an old mojoPortal intallation problem I already had that made me abandon mojoPortal setup a month ago. But this time I insisted and made it run.

The setup runs but it immediately gives an error: it gives errno: 105 as soon as it tries to create the second table. I googled around very deeply but didn't find anything specific (error 105 is a generic Foreign Key creation error, generally due to inconsistency between data types).

I finally found that ALL FOREIGN KEY statements in Setup/applications/mojoportal-core/SchemaInstallScripts/mssql/2.2.7.8.config have a mismatch in the named foreign table: it appears as lowercase:
CONSTRAINT `FK_mp_PagesSite` FOREIGN KEY (`SiteID`) REFERENCES `mp_sites` (`SiteID`)
gives errno:105

Changing every table name in every statement to the correct case:
CONSTRAINT `FK_mp_PagesSite` FOREIGN KEY (`SiteID`) REFERENCES `mp_Sites` (`SiteID`)
solved the problem and finally, after over a month of headaches made me proudly see my mojoPortal site.

Uh, I also had the no-skin problem as reported in this post and solved manually adding the
<add verb="*" path="*csshandler.ashx" type="mojoPortal.Web.UI.CssHandler, mojoPortal.Web" />
in Web.config.
Joe, it seems that the Web.config.mono is not updated with your last modifications to skinning.

Now I can start creating pages. Thank you all (particulary Joe)!
Hope this helps. Ciao.