Americans who attend a public school will usually become resident after one year and will thus qualify for in-state tuition for their subsequent years so you wouldn't think it would make too much of a difference. Internationals never gain residency, however, and this is a definite disadvantage in admissions, especially for UC's if the department is paying tuition.
For some purely anecdotal evidence: in my field, all PhD acceptances come with funding and the department offers to pay your tuition. Late January acceptances happen, but are somewhat rare (most occur in mid-Feb). I applied to twenty schools and have five offers so far: four of them from UC's (I'm a California resident). Make of that what you will I guess!