Active Auto released a tune for the N52 a while back. Decent gains for a N/A tune but required you to send your ecu or visit one of their local shops. However they've now released a handheld uploader, confirmed for the e90, but not yet for the Z4. I know when it comes to general coding our cars require an e46 style adapter / cable. I asked AA about this and whether or not their device was affected by this but they've yet to test it on a Z4.
So any Florida guys want to be the guinea pig and maybe get a discount out of this? I know they're definitely giving big discounts (possibly even free) for e90 330i owners, which share the same motor as our 3.0si.
New Tune:
http://www.e90post.com/forums/showthread.php?t=634855
Needing a 330i (3.0si):
http://www.e90post.com/forums/showthread.php?t=634715