Hard float support is now in mono 3.2.7:
http://www.raspberrypi.org/phpBB3/viewtopic.php?t=62496&p=468500
The latest source can be installed from git.
It should be something like this:
(remove previous mono installations first)
sudo apt-get update
sudo apt-get install git build-essential automake autoconf libtool gettext
git clone git://github.com/mono/mono.git
cd mono
./autogen.sh --prefix=/usr/local
make get-monolite-latest
make EXTERNAL_MCS="${PWD}/mcs/class/lib/monolite/gmcs.exe"
sudo make install
This is how "mono -V" looks like on my raspberry:
Mono JIT compiler version 3.4.0 (master/ae165c5 Thu Mar 13 01:20:37 UTC 2014)
Copyright (C) 2002-2014 Novell, Inc, Xamarin Inc and Contributors. www.mono-project.com
TLS: __thread
SIGSEGV: normal
Notifications: epoll
Architecture: armel,vfp+hard
Disabled: none
Misc: softdebug
LLVM: supported, not enabled.
GC: sgen
A quick test seems to work fine:
csharp> Math.Pow(2,4);
16