Hi i just downloaded BT4 beta and installed it to my usb. The first thing what i did was trying to update MSF. With the next results:
U    msfopcode
U    msfpescan
A    plugins/pcap_log.rb
U    msfelfscan
U    external/ruby-lorcon/test.rb
U    external/pcaprub/pcaprub.c
U    msfweb
U    msfmachscan
svn: Failed to add file 'scripts/meterpreter/remotewinenum.rb': object of the same name already exists
It looks like it was already update but the update was interrupted.