In developing an overlay for the Bowdoin College campus (kmz link here), it became apparent that overlays with a dimension of 2048 pixels or larger, regardless of file size, did not appear (ie were transparent) on some machines.

Using the newest build of Google Earth for Mac Beta (3.1.0621.0 (beta)) on 10.4.6 with a 64 MB AGP nVidia GeForce FX Go5200, Google Earth indicates that it supports 4096x4096 as the max texture size, and that it is using the NVIDIA NV34MAP OpenGL Engine (1.5 NVIDIA-1.4.18) video driver. However this system was unable to see these textures (originally aprox. 2300x2300, but now downsized).

Additionally, it may be useful to know that a different system configuration on the same build of Google Earth, but using video driver NVIDIA GeFroce4 MX OpenGL Engine ( 1.1 NVIDIA-1.4.18) indicated a max texture size of 2048x2048, but was still able to display textures over 2048 on a side.

**EDIT**
It turns out, this small scale down (from 2300 to 2048) only fixed this issue on some machines. Others are still unable to view the overlay. (For example, a computer with the same build as above, running 10.4.2 with graphics driver NVIDIA GeFroce4 MX OpenGL Engine ( 1.1 NVIDIA-1.4.6) indicated it could view overlays up to 2048x2048, but was unable to view our resized overlay.)

Now our big question is this:
We can spend some significant amount of time breaking our overlay down into many closely aligned smaller parts, to such an extent that the overlays load on all machines. However, if this issue will be fixed shortly with an update to Google Earth for mac, it will not be worth our while. So, can you provide us with any info about upcoming updates?