As the article notes, the addition of conservative imprints to major publishers is not uncommon, though it is a relatively new phenomenon. Random House has Crown Forum; Simon & Schuster has Threshold Editions; Penguin has Sentinel. Publishers can print Karl Marx and Sarah Palin side-by-side under different imprints, and as the Tea Party furor continues to mount over the next year or two, I expect publishers to begin printing a lot more of the latter.
There's a sizable minority in the publishing industry that says—or at least jokes—that conservative voters don't read, so publishing books that cater to them is a waste of time and money. I'm certain that the continued success of books by politicians/pundits/celebrities like Glenn Beck, Sarah Palin, and Sean Hannity, not to mention their perpetual presence on the New York Times bestseller list, fairly refutes this notion; there can't be that many liberals buying these books out of morbid curiosity.
So, with all the usual caveats that: I am not a seer; I am not speaking from any inside or non-public knowledge; I am not providing professional advice; I am not responsible for your lost time or money in the event you decide to go ahead and do this, &c: if you're writing conservative non-fiction, political analysis, or memoir, especially anything Tea Party-oriented, you might have more of a chance at representation and good sales than you think. Just, you know, try to avoid ranting.
My personal politics notwithstanding, I'm encouraged by this quote from Adam Bellow, son of Saul Bellow and head of Broadside Books: "What I intend to do is uphold a standard of intellectual seriousness on the right. [These books] should be written in a way that they are serious, soberly argued, well researched, and make a respectable case—agree or disagree." If your book is well-researched and well-written, I see no reason why you shouldn't give the Liberal Book Publishing Machine a try.