Obviously, this a good thing for Americans desperate for a return to fiscal sanity. And there are few lobbyist I find more obnoxious than Grover Norquist (Americans for Tax Reform) and Steven Moore (Club for Growth). But the real interesting question is, where now for the GOP? A few months ago, I argued that Tax Cuts were literally the only ideological bond shared by the Republican Party today. As I wrote then, beyond Tax Cuts
[w]hat, exactly, does the Republican Party have left? It doesn't have a commitment to Homeland Security, witness Bush's opposition to the DHS, 9/11 commission, and a myriad of other HS reforms. It doesn't have a commitment to small government, look at the Prescription Drug Coverage plan. It doesn't have a commitment to states rights, look at NCLB. It doesn't care about government non-intrusiveness, look at the FMA and the PATRIOT act. The closest thing to a coherent foreign policy it has is a commitment to democratization, which I support (and tragically, many Democrats have reflexively opposed despite it being a natural extension of liberal views), but even this appears to have stalled out beyond Afghanistan and Iraq (look at our anemic protests towards Putin's Russia, and our devil's bargain with Uzbekistan, for example). I would say Republicans like to blow things up, but then why is North Korea still on the map? It appears that LITERALLY the only thing that "unites" the Republican party is tax cuts, and that coalition simply can't hold together much longer.
Without cutting taxes (and reducing the size of government generally), there is nothing, literally nothing, that the Social Conservatives and Libertarian wings of the party have in common. There will be significant tensions in the old-guard GOPers as well, who like cutting taxes but (nominally, at least) value fiscal responsibility more.
The Washington Monthly article I linked to above notes that even in notoriously tax-averse Virginia, a group of stalwart Republican legislators managed to get passed a giant $1.8 billion tax increase, outstripping even the calls from Democratic Governor Mark Warner. Norquist and Moore have called for these legislators' heads, and are gunning for them in Virginia's 2005 elections. A very good indicator of the anti-tax zealots grip on power is how those elections turn out. If the maverick Republicans hold their ground, then that is a major crack in the wall.