Here is a link to the currently supported devices:
http://www.cisco.com/univercd/cc/td/doc/product/iaabu/csids/csids8/13870_01.htm#xtocid20
The main limitation for routers and switches is that IDS must be the sole
controller of the interface/directions which have been configured
for shunning. This has not changed since the older releases.
This does not apply to PIXes however. IDS uses a new shun command
on the PIX, so users can modify PIX ACLs whenever they wish.. The
main limitation for PIXes is that network shuns (as opposed to host shuns)
are not supported.