Wirelessly posted (Mozilla/5.0 (iPhone; U; CPU iPhone OS 2_1 like Mac OS X; en-us) AppleWebKit/525.18.1 (KHTML, like Gecko) Version/3.1.1 Mobile/5F136 Safari/525.20)
there's a few threads on the Apple discussion boards about iTunes 8 breaking airtunes. It stopped working on my mac mini after upgrading to iTunes 8, but before remote 1.1. I haven't had a chance to try fixing it yet, so cannot confirm what needs to be done. But they mention a few possible fixes like changing IPv6 to "automatic", or enabling iTunes access in the firewall.