From Adrian Wojnarowski:

DET and CLE negotiated down to wire on a Rip Hamilton trade, but fell apart when Rip wouldn’t accept buyout terms with Cavs, sources say.

And also this:

DET and CLE agreed on protected future draft pick to go with Hamilton, but Rip wouldn’t give back enough of $25M owed him, sources say.

Pistons also had an offer on the table from the Mavericks for Tayshaun Prince involving Detroit receiving the expiring contract of Caron Butler and a first-round pick, but apparently Detroit thought Prince could be more valuable in the summer as a sign-and-trade candidate than whatever would be available in the 25th+ pick.