Hi,
Haven't seen Cisco release any news of IOS train that support 32 bit AS number. Maybe next year.
In RIPE-NCC article dated October 2006, it mentioned that Cisco has an implementation but not officially announced. Juniper and RedBack has officially announced though. Unfortunately, all these will be available only on high end routers (according to the article).
See RIPE-NCC article http://www.ripe.net/ripe/meetings/ripe-53/presentations/32bit_asn.pdf
Regards,
Dandy