i just read that if i roll money into a roth and later unconvert in the same year to lower the tax bill, i can't reconvert until the following calendar year. is that so?

Effective January 1, 2000, a taxpayer converting a traditional IRA to a Roth IRA and subsequently recharacterizing ( unconverting)that conversion may not reconvert that amount until the year following the conversion or 30 days after the recharacterization, whichever is later.