Definitely looks like Riccia. I had that stuff tied down on my driftwood before, and it looked nice...for a while... but because I didn't keep it trimmed, the lower levels of the stuff started to die off because it wasn't getting enough light, to the point where it ended up just "tearing away" from the drifwood... you can see how it looks in one of my older videos of how my 15 gallon tank used to look...hehehe
[flash=425,350]http://www.youtube.com/v/7XuXzudPdSU" allowscriptaccess="always" allowfullscreen="true[/flash]
I would personally just leave it floating... people do like to tie it down onto rocks or driftwood, to make a nice foreground covering plant... but as it grows, it tends to float back up to the surface, as more of it starts to grow.
Really beautiful plant, if you can keep it tamed. I'm too lazy for that. =P