Channel 4 have recently launched a Watch Online web site, which allows you to watch the last 7 days programs from a web browser. iPlayer MCE has now been updated to include that content (version 1.3). To see the Channel 4 content, simply pick Channel4 from the channel list.

Since Channel 4 send their content as wmv rather than flash, it is also far better integrated with the VMC environment, with the content behaving like any local video (i.e. pause, fast forward and so on).