Several blogs have sprung up around the TiVo and general industry. In roughly chronological order:
PVR Blog - Written by Matt Haughey, this blog was one of the first to cover DVRs, and when it began, TiVo was really one of the only players. This is generally a very solid source of news, although the frequency of posts has become much more sporadic over time, and fewer and fewer posts are related to TiVo products.
Zatz Not Funny - Started by Dave Zatz and now with other contributors. Dave originally had an unrelated job, then seems to have gone into blogging full time, and now works with Slingmedia, recently bought by Echostar. So the focus on TiVo products here may be waning, but this is a very informative, fact-filled site.
TiVo Lovers - Maintained by "Megazone," who is generally well-know to TiVo forum participants, this blog covers TiVo and a wide range of video and tech related news, especially focused on HD.
TiVo Blog - The aptly-name TiVo Blog is written by Alex Rainoat. This blog has really become the most focused and most frequently-updated TiVo Blog. Alex scours the internet for information and consolidates it. This blog is generally updated several times each day.
WeaKnees Blog - WeaKnees, the largest online store dedicated to the TiVo area, has a blog about TiVo issues.
In addition, most TiVo products are covered on the major tech blogs from time to time including Gizmodo, Engadget, Engadget HD, etc.