Nokia6820/2.0 (4.83) Profile/MIDP-1.0 Configuration/CLDC-1.0 (compatible; Googlebot-Mobile/2.1; +http://www.google.com/bot.html)

DoCoMo/1.0/N505i/c20/TB/W20H10 (compatible; Googlebot-Mobile/2.1; +http://www.google.com/bot.html)

恐らくサイトマップ登録時に
XHTMLを選択すればNokia
CHTMLを選択すればDoCoMo

[参考]
Google Wireless Transcoder（AU検索時のproxy）

Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.0; Google Wireless Transcoder;)