They just cannot seem to leave it alone. A few years ago, the estate tax system at the federal level was a mess and became a political football even resulting in one year where the estate tax was completely repealed. After a few years of political fighting over the issue they finally settled on the current rule which has been in place now for a few years. The current federal estate tax provides for a $5 million (which is adjusted up annually) and includes portability and other features.
However, not content to leave well enough alone, the estate tax has again returned to the headlines when it featured in the recent State of the Union address in January. President Obama proposed some changes to the rule such as a prohibition against stepped-up basis and other provisions of the estate tax. While it will not affect a large number of people, from a policy perspective politicians just cannot seem to leave it alone probably because of the headlines it generates and less because constantly tinkering with the rule is good policy.
If you think you might inherit (or plan to leave) an asset that has appreciated substantially since it was purchased, you might want to review the proposed changes to the rule and potentially make an appointment with your estate planning advisor(s). While it is safe to say that not much will get done in the near term with a divided government, that may change in two years after the next presidential election. It is always smart to keep an eye on these rules just in case there is a substantive change that might affect your estate plan.