Mine

gmcs -out:Tomboy.exe -debug -define:DEBUG -unsafe -target:exe -define:ENABLE_DBUS -define:FIXED_GTKSPELL Tomboy.cs ActionManager.cs Applet.cs Logger.cs Note.cs NoteManager.cs NoteWindow.cs NoteBuffer.cs NoteTag.cs PluginManager.cs Preferences.cs RecentChanges.cs Tray.cs Trie.cs Undo.cs Utils.cs Watchers.cs XKeybinder.cs panelapplet/BonoboUIVerb.cs panelapplet/ChangeBackgroundHandler.cs panelapplet/ChangeSizeHandler.cs panelapplet/GnomeSharp.PanelAppletFactoryCallbackNative.cs panelapplet/MoveFocusOutOfAppletHandler.cs panelapplet/ObjectManager.cs panelapplet/PanelApplet.cs panelapplet/PanelAppletBackgroundType.cs panelapplet/PanelAppletFactory.cs panelapplet/PanelAppletFactoryCallback.cs panelapplet/PanelAppletFlags.cs dbus-sharp/dbus-sharp/src/Address.cs dbus-sharp/dbus-sharp/src/AssemblyInfo.cs dbus-sharp/dbus-sharp/src/Authentication.cs dbus-sharp/dbus-sharp/src/Bus.cs dbus-sharp/dbus-sharp/src/BusObject.cs dbus-sharp/dbus-sharp/src/Connection.cs dbus-sharp/dbus-sharp/src/DBus.cs dbus-sharp/dbus-sharp/src/DProxy.cs dbus-sharp/dbus-sharp/src/ExportObject.cs dbus-sharp/dbus-sharp/src/Introspection.cs dbus-sharp/dbus-sharp/src/Mapper.cs dbus-sharp/dbus-sharp/src/Message.cs dbus-sharp/dbus-sharp/src/MessageFilter.cs dbus-sharp/dbus-sharp/src/MessageReader.cs dbus-sharp/dbus-sharp/src/MessageWriter.cs dbus-sharp/dbus-sharp/src/Protocol.cs dbus-sharp/dbus-sharp/src/Server.cs dbus-sharp/dbus-sharp/src/Signature.cs dbus-sharp/dbus-sharp/src/SocketTransport.cs dbus-sharp/dbus-sharp/src/Transport.cs dbus-sharp/dbus-sharp/src/UnixNativeTransport.cs dbus-sharp/dbus-sharp/src/UnixTransport.cs dbus-sharp/dbus-sharp/src/Wrapper.cs dbus-sharp/dbus-sharp-glib/glib/GLib.IO.cs dbus-sharp/dbus-sharp-glib/glib/GLib.cs RemoteControl.cs RemoteControlProxy.cs Defines.cs -r:/usr/lib/pkgconfig/../../lib/mono/gtk-sharp-2.0/pango-sharp.dll -r:/usr/lib/pkgconfig/../../lib/mono/gtk-sharp-2.0/atk-sharp.dll -r:/usr/lib/pkgconfig/../../lib/mono/gtk-sharp-2.0/gdk-sharp.dll -r:/usr/lib/pkgconfig/../../lib/mono/gtk-sharp-2.0/gtk-sharp.dll -r:/usr/lib/pkgconfig/../../lib/mono/gtk-sharp-2.0/glib-sharp.dll -r:/usr/lib/pkgconfig/../../lib/mono/gtk-sharp-2.0/gnome-sharp.dll -r:/usr/lib/pkgconfig/../../lib/mono/gtk-sharp-2.0/art-sharp.dll -r:/usr/lib/pkgconfig/../../lib/mono/gtk-sharp-2.0/gnome-vfs-sharp.dll -r:/usr/lib/pkgconfig/../../lib/mono/gtk-sharp-2.0/gconf-sharp.dll -r:/usr/lib/pkgconfig/../../lib/mono/gtk-sharp-2.0/gconf-sharp-peditors.dll   -r:Mono.Posix -resource:../data/GNOME_TomboyApplet.xml,GNOME_TomboyApplet.xml -resource:../data/DefaultPlugins.desktop,DefaultPlugins.desktop -resource:../data/UIManagerLayout.xml -resource:../data/images/tomboy.png,tomboy.png -resource:../data/images/tomboy-note-16.png,tomboy-note.png -resource:../data/images/gnome-searchtool.png,gnome-searchtool.png -resource:../data/images/pinup.png,pinup.png -resource:../data/images/pinup-active.png,pinup-active.png -resource:../data/images/pindown.png,pindown.png
NoteBuffer.cs(16,28): error CS1012: Too many characters in character literal
Compilation failed: 1 error(s), 0 warnings
make[3]: *** [Tomboy.exe] Error 1
make[3]: Leaving directory `/var/tmp/portage/app-misc/tomboy-0.5.2/work/tomboy-0.5.2/Tomboy'
make[2]: *** [all-recursive] Error 1
make[2]: Leaving directory `/var/tmp/portage/app-misc/tomboy-0.5.2/work/tomboy-0.5.2/Tomboy'
make[1]: *** [all-recursive] Error 1
make[1]: Leaving directory `/var/tmp/portage/app-misc/tomboy-0.5.2/work/tomboy-0.5.2'
make: *** [all] Error 2

!!! ERROR: app-misc/tomboy-0.5.2 failed.
Call stack:
  ebuild.sh, line 1580:   Called dyn_compile
  ebuild.sh, line 945:   Called src_compile
  ebuild.sh, line 1269:   Called gnome2_src_compile
  gnome2.eclass, line 71:   Called die

!!! compile failure
!!! If you need support, post the topmost build error, and the call stack if relevant.