Wirelessly posted (Mozilla/5.0 (iPod; U; CPU iPhone OS 4_2_1 like Mac OS X; en-us) AppleWebKit/533.17.9 (KHTML, like Gecko) Version/5.0.2 Mobile/8C148 Safari/6533.18.5)
Apple rewrote the SMB stack in Lion, mainly because they didn't want to use the GPLv3 version of Samba. It might take them a few updates to iron out the bugs and so forth of their new implementation, which I think is called SMBX.