Looking at Ric Flair's '02 Cagematch based on the discussion of '02/'03 Hogan in the Old School Observations thread.
Internet Wrestling Database
www.cagematch.net
I DID NOT KNOW that Ric Flair made a cameo in OVW, doing a rare team up with his son David against Sean O'Haire and some go nowhere failed prospect named The Prototype*!
*(all kidding aside, is this the only time that John Cena and Ric Flair ever were in the same match besides maybe a Rumble? Flair retired in the dying days of the brand split era and they always seemed like they were on different shows.)
Edit- it looks like they tag teamed a few times in late '05/early '06 and in an eight man tag with DX in the build up to WrestleMania XXIV when they were both on RAW. It does look like the OVW match was only time they wrestled each other though.
At least until now. Cena, please don't wrestle septuagenarian Flair.