Because trademarks are so strongly linked to commerce, a person developing software may deal with the other areas of IP more than with trademarks. At the stage of GUI development and distributing or selling products however, trademarks can become important to the developer. For example, the distributors of LindowsOS software were sued by Microsoft for infringing the trademark in Windows. (As of this drafting, the Judge had issued preliminary rulings favorable to Lindows, but the case had not been resolved.) 
Because the law defines trademark infringement very broadly,  anyone who might become involved in this area should tread carefully.
Additionally, people should be mindful of registering Internet domain names that are identical or similar to trademarks . Under both U.S. law and ICANN's Uniform Domain Name Dispute Resolution Policy (UDRP), if a word being used as a domain name is trademarked, the trademark holder often has the power to stop the infringing use and recover the domain name, particularly if the registrant only "squatted" the domain in hopes of extorting money from the trademark holder. However, just like in the physical world, two entities can have equal right to a single word (Bass Ale and Bass shoes for example). And in some cases, a registrant who has no trademark but who was the first to claim the domain name has superior rights to the domain name (a bass player or fishing enthusiast who registered bass.com, for example).  It is important to note that the UDRP continues the trend to allow the first-come-first-served approach to domain name allocation. If someone with a legitimate, but non trademarked, claim to the mark uses it on the Internet, they will still have some power to defend themselves. Sections 4(b) and 4(c) of the UDRP describe how a dispute between a trademark holder and a domain name holder might arise, and how the domain name holder might win.