Israeli news source Jerusalem Post has just announced on its LiveBlog that it has begun a ground invasion:
IDF ground forces began to move into the Gaza Strip on Thursday evening, the prime minister’s office confirmed.
The purpose of the operation was to destroy the Gazan terror tunnels leading to Israel, according to a statement released by the prime minister’s office.
Prior to the commencement of the ground invasion, the IDF launched a massive wave of combined air and artillery strikes on Thursday night.
The IDF said that the operation will involve infantry, engineering corps, and tank units combined with air force and naval support and intelligence.