Found an Issue with IPv6 SLAAC on WLAN Interface of MacBook Pro Lion.
Using IPv6 SLAAC provided by my Internet Router (RA send with Multicast and Unicast) me MacBook can get an IPv6 address at Ethernet Interface without any problem, but if I connect to the same Router over WLAN the Lion cannot get any IPv6 address. Using another Laptop with Mountan Lion connecting to the same Router by WLAN it can get IPv6 address without any problem.
So I can defently rule out a Problem by the SLAAC setup of the Router as Mountan Lion can work with it and also some Windows and IOS Devices are fin with IPv6 over WLAN access. Just Lion seems not be capable to receive SLAAC IPv6 address over WLAN but only over the wired Ethernet connection.
Anybody aware of this Issue? Solution (anything else as update to Mountan Lion :-))