Long has it been promised and well before Sony has made its broadband a reality, SEGA has released its broadband adapter for the Dreamcast. The following is a quote from the Gaming Intellegence Agency:
After months of anticipation, the Dreamcast Broadband Adapter is finally available at Sega’s online store. The adapter allows gamers to connect with any existing Ethernet, DSL, or Cable network. Though only a few of the system’s networkable games are supported, the highly anticipated Phantasy Star Online will be one of the first marquee titles to take advantage of the Adapter’s broadband capabilities.
Source: The Gaming Intellegence Agency