Let us have a moment of silence for James McCombe's GLTerminal.
There, now that that's over with, go check out the spiritual successor to GLTerminal: Secret Geometry's Cathode terminal emulator.
If you like GLTerminal but realize deep in your heart that it will never see any more love or updates from its creator, check out Cathode. It has fully replaced James McCombe's ancient, broken, and Spaces-unaware GLTerminal for me. It degrades in quality until you purchase a license... brilliant! Go buy it ($20) and support Colin, an active Mac developer!
*Note: I do not know if this is also only a Macbook/Nvidia issue (I only have a Unibody 13" Macbook Pro with 9400M GPU to test it on).