Yes, it is April 1st, and Kerio's site hasn't really been hacked. They just thought this might be a fun way to call attention to the importance of firewalls today and of course specifically their Kerio WinRoute Firewall.
I don't sell a lot of these. I've written before about the comparison of this to dedicated hardware units and the advantages and disadvantages of both. I think there is a good case to be made for this (see that link for why) but the most important point is that many small businesses go really cheap on firewall protection, using $100 or less appliance routers found at Staples or Best Buy to protect their networks. I don't think that makes a lot of sense - it's not necessarily a matter of protection (though that may indeed figure in) but more importantly a matter of flexibility - it's when you start opening up those cheap routers for necessary services that you run into their limits. A real rule based firewall like KWF or Fortinet provides far more control.