The thing that's most striking about the poster - beside it being passed around in Dallas in 1963 - is that it is literally accusing him of treason, and thus arguing he is a domestic threat. It is a clear declaration that the US president is an enemy of state and must be dealt with; Something must be done. And we're seeing the same type of language being used against Obama, as it was against Clinton. Sure there were similar charges against Bush, but not to the level we're seeing now, or saw in the 90s.
If this was regulated to the crazies on the far right I wouldn't really be concerned. But mainstream republicans give this stuff credence every single day by arguing there is something so radical and different about Obama that he is a huge threat to America, sympathizes with our enemies, etc; they are clearly sending the message that Obama is a domestic threat. When you consider how far right wing organizations attempt to recruit former military folks, this type of shit becomes even more odious
If Obama wins big, as polls show (right now), I think it's clear the far right will go even more insane than they have over the last few years. Anyone who payed attention in October 08 knew McCain was going to lose. This time the far right has created their own polling reality to ensure people truly believe Obama has no chance of winning. We're going to see some crazy shit, bros