An important part of being a lawyer is accessing information, assessing its credibility, and then using it to your client's advantage. Wikipedia is a fantastic source of information. You need to always be careful to assess credibility because just about anyone can add anything to a Wikipedia entry, but in my experience Wikipedia has been a great way to quickly learn about a topic.
You can access the Wikipedia web pages on your iPhone in Safari, but the text can be a little small. Thus, there are a number of iPhone apps that aim to make it easier to access Wikipedia. My favorite has always been Wikipanion, an app that doesn't deserve placement on my iPhone's first home screen but does go on the top of the second page.
For example, in my November 26, 2008 entry on iPhone J.D., I mentioned the right to privacy and I wanted to give a quick link to something discussing the fact that the right is not explicitly referenced in the U.S. Constitution. So I fired up Wikipanion and typed "Right to Privacy" at the search bar at the top. At the top of the screen, Wikipanion will show you any articles that have a title relating to your search terms, or you can tap "Full Wikipedia Search" to look for that phrase in an article. That brought me to a screen with a bunch of possible hits, and the eighth one down is Griswold v. Connecticut. Tap once on that entry, and you can see the full Wikipedia entry on the landmark Griswold case, formatted nicely for the iPhone screen.
The excellent site iLounge recently reviewed 16 different iPhone apps that give you access to Wikipedia, and Wikipanion is also their favorite. In fact, they give it an "A" rating, and that is really saying something because iLounge is not known for being generous with their grades; lots of apps and accessories that I love only get a B+ or A- from iLounge. If you are interested in accessing Wikipedia on your iPhone, you should definitely take a look at the iLounge article. Also, the Wikipanion website has lots of great information about Wikipanion and its $5 big brother, Wikipanion Plus (which adds more features such as the ability to download a Wikipedia page so that you can access it later even when you are not connected to the Internet).
Click this button to download Wikipanion for free from iTunes.