Effective July 1, the IRS mileage reimbursement rate will increase to $0.585 per mile. That's an $0.08 increase. This rate will remain in effect for the remainder of 2008.
The reimbursement rate for reimbursement of mileage for medical issues and moving also goes up $0.08 to $0.27, up from $0.19.
The IRS's announcement is here.