The first England home game, England v Italy, is to be broadcast on BBC HD on Saturday February 7th, coverage starting at 2pm. On Sunday, 8th at 2.30 there's coverage of Scotland v Wales. The following Saturday has Wales v England. As with previous years, it appears that the games from France or Italy are not being shown in HD - just those from the UK.
Here's a useful guide to Rugby (and other sports) coverage on the telly.
Disappointing news again though for SuperBowl fans: the BBC is only showing it on BBC1. If you want to see it in HD, you need a dish :o(