I agree that an open laser show format would be nice. However, Bill Benner has a point... You *can* use the ILDA file format to export an entire show. Sure, you get a very large series of frames, and there is a lot of duplication, but it works. So long as you specify a frame rate and a scan rate (which can be included in a simple text file), anyone can play back the show exactly as it was created.
To borrow Marc's analogy - if I whip up an audio composition using Acid or Reason, I can send the relatively small track info file to someone else that has the same software (and the same audio loop files) and he can re-create the song I composed. But if I want to sent my composition to someone that doesn't have Acid (or Reason), then I need to export the song as a .wav file and send it that way. Sure, the file size is a lot larger, but the other guy can still play it.
The real problem with a common show format (one that includes both frame data and effects) is that there may be certain effects that are supported on some controllers (or software packages) that are not supported on others. Likewise, there may be different ways to accomplish the same effect, again depending on the controller or the software. (Consider the wide variety of abstract generators, or the Alphalite's "sine" format, which is unique to that controller...)
Then there's the whole digital rights management issue. Copyright infringement can be a serious problem, and developing an open file format that still respects the content owner's copyright is not going to be easy.
Given these limitations, I can see why ILDA was chosen as the standard. Yeah, it's cumbersome to export an entire show as a series of frames (you end up with some very large files!) but it *does* work...
Still, I have to admit that it *would* be nice to have an open show format. I just don't think we're going to see one any time soon.
Adam