I have had really good reception tonight, and scanning around I came across a Radio Marti broadcast being jammed by Cuba (I am assuming it is Cuban). First, the details:
Radio Marti :0738 UTC - 0745 UTC, 6030 Khz. SIO 312. Male and Female have a conversation in Spanish. Jamming being broadcast over program (sounds like running water / brook).
Checking Passport to World Band Radio, it confirms Radio Marti at that time and frequency, and that the broadcast is jammed.
Listen to sample of Radio Marti Broadcast being Jammed
The jamming is not as clear on the recording, but you can hear it. It sounds like a babbling brook being broadcast over the Radio Marti broadcast.
You can find another report / example of the jamming here, and an analysis of the jamming here.
More information on Radio Marti at wikipedia.