It turns out Alter Shortcuts, e.g Alt+R (Reply), Alt+L (Reply All), and Alt+W (Forward), no longer work in Outlook 2010 BETA at all, though they worked in Outlook 2007 and previous Office 2010 CTP version.
Actually, these shortcuts are not lost, they just change Alt to Ctrl for some reason. Users have to use Ctrl+R to Reply instead of Alt+R, use Ctrl+Shift+R to Reply All Instead of Alt+L, use Ctrl+F to Forward Instead of Alt+W.
Hopefully MS won’t change these again in RTM builds.
22th April – Microsoft brings them back in final Office 2010 RTM build 14.0.4763.1000, the shortcuts for reply and forward are same as Office 2007
Reply: Alt+R or Ctrl+Shift+R
Reply All: Alt+L