Using tomato-K26USB-1.28.9054MIPSR2-beta-vpn3 on Asus RT N16.
HD format: NTFS, FAT32 and (now) ext3
Media Server seems to work with my PS3 (DLNA). File sharing also ok (Samba: Mac and PC).
Tivo will only detect the media server after the router has been recently reboot. Initially, it will work, but will stall mid transfer and then disappear from the HME list. Other Tivo HME devices (Tivo Desktop, and PyTivo) continue to work fine.