The IRS will be revising Pub 590 due to a recent Tax Court ruling (Bobrow, TC Memo. 2014-21). Although the government publication indicates that IRA rollovers are allowed once a year from each IRA, the Tax Court has ruled that the IRS has been interpreting tax law incorrectly.
Apparently, if the taxpayer takes a payout from multiple IRAs within a 12 month period, all but the first are taxable, EVEN IF HE/SHE PUTS ALL THE FUNDS BACK WITHIN THE 60 DAY PERIOD.
The only way to avoid this is using trustee-to-trustee transfers. They are not subject to the 12 month rule since they are not considered rollovers.
Moral of the story: Watch your timing carefully — or use your trustee!