Question: I keep accidentally dragging windows into other workspaces on my Macbook Air running OS X Lion.

Can I disable dragging into other workspaces or make doing so more difficult?

Answer: 
There's a hidden preference for adjusting the delay in seconds:

```
defaults write com.apple.dock workspaces-edge-delay -float 0.5
osascript -e 'quit app "Dock"'

```

It can be set to an arbitrarily high value to disable dragging windows to other spaces.
TinkerTool has this option in the Applications tab, Mission Control, Delay when dragging window to adjacent space: Default / Short / No Delay.  

No Delay was selected on my computer, but I don't remember if I chose that at some point. I looked into this because I wanted the "windows aero snap" feature, I just found and installed [Cinch by Irradiated Software](http://www.irradiatedsoftware.com/cinch/). The Spaces "swipe" would happen before Cinch was able to do its thing.