It is a new feature in Xfce 4.10:http://www.xfce.org/about/tour
(look at the bottom)
But... that hasn't reached the repos yet. Actually, it hasn't even fully reached the debian experimental repo.
So, i will be some time until it trickles down to LMDE. Unless you want to try compiling it from source.
Anywho, in the mean time, there is a little hack you can do that will make this aero snap-like feature in 4.8...
I've had it running for a few months now, and it seems to be working well enough. A little glitchy sometime on the resizing. But it's hardly noticeable.
This does require compiling and patching 4.8 (for fedora, but you can make it for LMDE), but if you're interested, take a look:http://notanothersheep.com/XFCE4WindowTiling
You'll probably want to change your sources to SID temporarily for the dependencies if you try this.
I'll warn you though, it could get messy. Didn't for me, but then again, every system is different.