Merrick describes his style of music as "synthesiser music with samples and heavy guitars". Rockstar are remaining tight-lipped about any details regarding the game, so again we we have no confirmation on whether or not he will feature in GTA4. You can visit his website for some samples of his music.
"I was contacted by someone who has heard my songs on the website. They wanted a track they could use on the car radio as people are driving round the game."
This isn't the first rumour we've heard regarding soundtrack details, the first appeared as a topic on a forum (which was promptly removed) where 80's New York-based band Breakdown were allegedly contacted by Rockstar Games.
If both these rumours turn out to be true it seems like we'll be hearing quite a few different types of music in the game, just as we have in previous iterations.
Thanks to gta4.net for the heads up.