I'm not sure how credible this is right now, but AlaskaReport says:
AlaskaReport has learned this morning that Todd Palin and former Alaska governor Sarah Palin are to divorce. Multiple sources in Wasilla and Anchorage have confirmed the news.
A National Enquirer story exposing previous affairs on both sides led to a deterioration of their marriage and the stress from that led to Palin's resignation as governor of Alaska.
The Palins were noticeably not speaking to each other at last Sunday's resignation speech in Fairbanks. Sarah ditched Todd (MSNBC) right after the speech and left without him. Sarah removed her wedding ring a couple of weeks ago.
If true, another family values sanctity-of-marriage wingnut epic fail.
But as Sarah Palin has said before: position flexible.
UPDATE: I want to underscore that this appears to be just a rumor. Hence, the above qualifiers: "apparently," "I'm not sure how credible this is" and "if true." However, considering the trend of sanctity-of-marriage Republicans being caught in extramarital affairs, this isn't outside the realm of possibility. And for the record, this sentence is possibly the first time I've ever mentioned the Trig "conspiracy" on this blog.