Earlier today, National Journal got in touch with Pence's mother, who predicted that he would make an announcement tomorrow -- though she would not say just what the announcement would in fact be.
However, as Roll Call reports, Pence is expected to announce today that he will not run for president, rather than say so tomorrow.
Also earlier today, former House Majority Leader Dick Armey (R-TX), now head of FreedomWorks, said that Pence could potentially be a second coming of Reagan. Oh Pence, why have you forsaken Armey?
Late Update: And it's official, the Indianapolis Star reports:
"In the choice between seeking national office and serving Indiana in some capacity, we choose Indiana," Pence, R-Columbus, said of himself and wife Karen in a letter being sent to supporters. "We will not seek the Republican nomination for president in 2012."
He said he would make a decision "later this year" about what his next political step is, but by not running for president it is considered a virtual certainty that he will run for the GOP nomination for governor.