Yes, Its available.
Here is a link that points to a configuration guide for a wlc 2500, 7.5.
http://www.cisco.com/c/en/us/td/docs/wireless/controller/7-5/config_guide/b_cg75.pdf
"The splash page web redirect feature is available only for WLANs that are configured for 802.1X or
WPA+WPA2 Layer 2 security with 802.1x key management."
