The recent propensity of the US Patent Office to allow the patenting of computer software is stirring much controversy. The two most notable such patents are that of the RSA Data Encryption Algorithm and the Unisys LZH Patent.
Some attempts are ongoing to come up with some sort of free software license to discourage the problems that can result from patents; see Advogato's Number: Patents, and www.bustpatents.com - Internet Patent News
The text of the patent is available at High speed data compression and decompression apparatus and method - US Patent 4558302 - LZW Compression. The patent was issued in 1985, which means that if the 17 year expiry effective at that time holds for this patent, it will expire near the end of 2002.
Unisys have been offering Web Site LZW Licenses at the "low, low price" of $5000 per web site.
There are other opinions on the matter; the most visibly "inflammatory" is the Burn All GIFs Day site.
Note that LZH compression is mandated for and thus affects the following fairly common data formats:
GIF - Graphics Interchange Format.
If the use of GIF files is outlawed, this would encourage the use of alternative formats called JPEG and PNG.
It would eliminate the use of "Animated GIFs" on the Internet, which might actually be a good thing.
Adobe Postscript Compression
Adobe Type 1 fonts
Adobe PDF documents