DVPRemote, which I originally came across back in August, has just received a substantial refresh. In addition to fundamental WiFi remote control of Roku’s media streamer ($99), the app author has worked closely with Roku to incorporate their graphics, enable auto-discovery (versus direct IP address entry), and add support for multiple units. I’ve had a preview copy of version 1.2 about a week and it operates as advertised. Grab it here for only 99 cents: 
i.TV, the premiere iPhone television guide and then some, is cooking up Roku remote support as well. The initial version out of their beta labs doesn’t include auto discovery, but i.TV has beefed up virtual remote functionality to support multiple (TiVo) units as requested. I played matchmaker between Roku and i.TV to get this remote going, which would explain my pre-release screengrabs below. Expect the free i.TV 2.1 to hit next month, but you can download the current release here:
Hey, thanks for the tip! I downloaded, rebooted iPhone, turned on the TiVo’s network control, and i.TV found my HD TiVo right away. The controls are excellent and the TV Guide is great, especially in landscape! Wow…just wow.