Nokia's new lawsuit against Apple, filed in the US Federal court of the Western District of Wisconsin on Friday, takes aim at the iPhone and iPad 3G for allegedly infringing upon five Nokia patents. This is just the latest dispute in an increasingly litigious smartphone market.

If all the name calling and legal barbs that have been flying around have your head spinning, here's a quick guide to sort things out:

Nokia vs. Apple/Apple vs. Nokia

Nokia's latest filing against Apple, made in May, charges Apple with infringing upon patents related to speech enhancement and data transmission technologies. The infringement, according to Nokia, involves techniques for data positioning in apps as well as antenna setups used to conserve space in compact handhelds. 

Nokia really got the action started in October by filing a suit against Apple in federal court alleging tht the iPhone infringes on 10 of Nokia's patents related to technologies such as GSM, UMTS and wireless LANs

Apple fired back in December, accusing Nokia of allegedly infringing on 13 of its patents and pointedly told Nokia that "other companies must compete with us by inventing their own technologies, not just by stealing ours." Apple also accused Nokia of antitrust violations and deceptive practices in terms of revealing its intellectual property rights.  Apple is also seeking a ban on US imports of Nokia gear.

The US International Trade Commission is also investigating each company's claims against the other. A US judge has put the earlier suits on hold while the ITC does its work. 

Family of author Philip K. Dick vs. Google

Author Philip K. Dick's estate said in January it would sue Google for allegedly swiping the names "Android" and "Nexus One" from Dick's 1968 novel "Do Androids Dream of Electric Sheep?" - which later morphed into the movie Blade Runner. "Google takes first and then deals with the fallout later," Dick's daughter Isa is quoted as saying in The Telegraph.

Google, which denies infringing on the Dick family's intellectual property introduced its Android-based Nexus One phone at CES in January.

Kodak vs. Apple and RIM

Kodak in January filed a lawsuit with the US International Trade Commission against Apple and RIM for allegedly infringing on patents related to digital imaging technology. Specifically, Kodak alleges that the Apple iPhone and certain BlackBerry smartphones are using a method for previewing camera phone images that has been patented by Kodak.

Motorola vs. Research in Motion

Patent litigation between Motorola and Research In Motion heated up in January, with Motorola filing a complaint with the US International Trade Commission alleging that RIM engages in unfair trade practices by importing and selling products that infringe five Motorola patents. The patents cover technologies related to Wi-Fi access, application management, user interface and power management, Motorola said.

Motorola is asking the ITC to investigate RIM and bar the company from importing, marketing and selling products in the US that use the technologies. The companies have been engaged in patent infringement suits dating back to early 2008. RIM declined to comment on Motorola's filing with the ITC.

Apple vs. HTC

Apple filed a patent infringement lawsuit at the start of March against HTC, claiming that the Taiwanese company is infringing 20 Apple patents are related to the iPhone user interface and the smartphone's underlying architecture and hardware. The lawsuit was filed in the US District Court in Delaware and with the US International Trade Commission.

The suit is seen by many as more a case of Apple vs. Google and even Microsoft than Apple vs. HTC.  HTC phones include those that use Google's Android mobile OS and Windows Mobile OS. HTC has defended itself, saying it uses its own technology, not Apple's. 

IDG News Service and PC World contributed to this article