Same here, but only with my work account (Exchange 2010) - works fine with my (hosted) personal Exchange account (which is on Exchange 2007 AFAIK).
It's been this way with all ICS leaks. Yesterday I thought I got it working by adding the accounts the other way around, but today I'm getting connection error again. I think it's got something to do with the Device Administrator setting, because I never get that prompt for the second account I add, whereas I'm pretty sure I did on GB.
Using Enhanced Email in the meantime which works fine, but the Samsung client has some great features :)
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Devices: Motorola Xoom | Point Of View Mobii Tegra 3G Tablet (P10AN01 / Advent Vega clone) | Samsung Galaxy S GT-I9000 | Samsung Galaxy S II GT-I9100 | Google Galaxy Nexus