I couldn't get more than 1.2 to 1.4 under Linux with latest versions of cgminer and bfgminer. Bfgminer for windows from the support thread works and I am getting 2.3Ghs

I have got a pi on order so will try again when that arrives.
I spoke too soon, pool average settles at 1.3Ghs on Windows as well

My Pi is giving an average of 2.33 on MinePeon, with an average of 2.24 at the pool. No special mods, no special drivers, just:- -S BPM:all
Reject rate is 0.81% Error rate is 59.23%
simple maths says this is not a true error rate.
2.33Gh less 0.81% = 2.311Gh pool shows 2.24Gh so corrected error rate is 3.07% The extra 56.16% is probably down to running a 5Gh chip at less than 2.5Gh.