Health-care reform: the new abortion?
I think it's an assertion of tribal identity, a feel-good vote for the far-right base. For years, abortion served Republicans in that role -- they could vote to ban it in this or that state, knowing that Roe v Wade would prevent prohibition from taking effect. Thus they won brownie points with their own base, without having to suffer the electoral consequences of actually taking a vital right away from women.
In the same way, a Republican vote to repeal HCR will solidify teabagger support -- without the political risk of actually taking away benefits from the broader mass of voters, since repeal can't actually take effect.