A new API method was added to perform redirects:
t3lib_div::redirect($url, t3lib_div::HTTP_STATUS_303);
Status can be any of the following constants:
t3lib_div::HTTP_STATUS_100
t3lib_div::HTTP_STATUS_101
t3lib_div::HTTP_STATUS_200
t3lib_div::HTTP_STATUS_201
t3lib_div::HTTP_STATUS_202
t3lib_div::HTTP_STATUS_203
t3lib_div::HTTP_STATUS_204
t3lib_div::HTTP_STATUS_205
t3lib_div::HTTP_STATUS_206
t3lib_div::HTTP_STATUS_300
t3lib_div::HTTP_STATUS_301
t3lib_div::HTTP_STATUS_302
t3lib_div::HTTP_STATUS_303
t3lib_div::HTTP_STATUS_304
t3lib_div::HTTP_STATUS_305
t3lib_div::HTTP_STATUS_307
t3lib_div::HTTP_STATUS_400
t3lib_div::HTTP_STATUS_401
t3lib_div::HTTP_STATUS_402
t3lib_div::HTTP_STATUS_403
t3lib_div::HTTP_STATUS_404
t3lib_div::HTTP_STATUS_405
t3lib_div::HTTP_STATUS_406
t3lib_div::HTTP_STATUS_407
t3lib_div::HTTP_STATUS_408
t3lib_div::HTTP_STATUS_409
t3lib_div::HTTP_STATUS_410
t3lib_div::HTTP_STATUS_411
t3lib_div::HTTP_STATUS_412
t3lib_div::HTTP_STATUS_413
t3lib_div::HTTP_STATUS_414
t3lib_div::HTTP_STATUS_415
t3lib_div::HTTP_STATUS_416
t3lib_div::HTTP_STATUS_417
t3lib_div::HTTP_STATUS_500
t3lib_div::HTTP_STATUS_501
t3lib_div::HTTP_STATUS_502
t3lib_div::HTTP_STATUS_503
t3lib_div::HTTP_STATUS_504
t3lib_div::HTTP_STATUS_505
More info:
RFC: #9281: Add a method to easily do a HTTP redirect
http://bugs.typo3.org/view.php?id=9281
RFC #11357: Consistency cleanup: Make use of new t3lib_div::redirect function throughout the core
http://bugs.typo3.org/view.php?id=11357