Hello,
I just baught a new MabBook Pro Retina, which has no IR port, so no Apple Remote compatibility.
After reading ministrybymouse comments, I thought I'd give a try with the R400.
It works perfectly with PowerPoint (v14.1, Office Mac 2011). The R400 is actually just a Keyboard with 4 preseted key that replicate the keyboard shortcut you would use with MPP. Left and right buttons act as "Page Up" and "Page Down", which are the same shortcut for goin through slides with Keynote. When pressing the "play" button, it acts alternatively as "F5" (play slideshow) and "ESC" (quit slideshow). Black screen button acts as "." key.
By remapping the keyboard layout of the R400 you can actually control Keynote very easily.
For this, I used a keyremap4macbook (free: http://pqrs.org/macosx/keyremap4macbook/). This plugin allows you to remap keyboard, selectively for application and devices. You can create your own costumized remapping in the so called "private.xml" file.
Here is a copy of mine. It allows full presenter controle for both PowerPoint and Keynote. (It also controle my music play when not in neither of the before-said applications).
I hope it'll help some of you.
Cheers
For Logitech: If your gear works on Mac OS X, why don't you say it ? 
<?xml version="1.0"?>
<root>
<devicevendordef>
<vendorname>LOGITECH</vendorname>
<vendorid>0x046d</vendorid>
</devicevendordef>
<deviceproductdef>
<productname>LOGITECH_R400</productname>
<productid>0xc52d</productid>
</deviceproductdef>
<appdef>
<appname>IWORK_KEYNOTE</appname>
<equal>com.apple.iWork.Keynote</equal>
</appdef>
<appdef>
<appname>POWERPOINT</appname>
<equal>com.microsoft.Powerpoint</equal>
</appdef>
<item>
<name>Costum making for Logitech R400</name>
<item>
<name>R400 For Keynote</name>
<identifier>private.R400_for_keynote</identifier>
<only>IWORK_KEYNOTE</only>
<device_only>DeviceVendor::LOGITECH, DeviceProduct::LOGITECH_R400</device_only>
<autogen>--KeyToKey-- KeyCode::DOT, KeyCode::B</autogen>
<autogen>
--KeyToKey--
KeyCode::F5,
KeyCode::P, ModifierFlag::OPTION_L | ModifierFlag::COMMAND_L
</autogen>
</item>
<item>
<name>R400 For music control</name>
<identifier>private.R400_for_music</identifier>
<not>IWORK_KEYNOTE</not>
<not> POWERPOINT</not>
<device_only>DeviceVendor::LOGITECH, DeviceProduct::LOGITECH_R400</device_only>
<autogen>--KeyToKey-- KeyCode::PAGEUP, KeyCode::VK_CONSUMERKEY_MUSIC_PREV</autogen>
<autogen>--KeyToKey-- KeyCode::PAGEDOWN, KeyCode::VK_CONSUMERKEY_MUSIC_NEXT</autogen>
<autogen>--KeyToKey-- KeyCode::ESCAPE, KeyCode::VK_CONSUMERKEY_MUSIC_PLAY</autogen>
<autogen>--KeyToKey-- KeyCode::F5, KeyCode::VK_CONSUMERKEY_MUSIC_PLAY</autogen>
<autogen>--KeyToKey-- KeyCode::DOT, KeyCode::F4, ModifierFlag::CONTROL_L </autogen>
</item>
</item>
</root>
