The online writing lab at Purdue University summarizes the most important changes this way:

• No More Underlining! Underlining is no more. MLA now recommends italicizing titles of independently published works (books, periodicals, films, etc).
• No More URLs! While website entries will still include authors, article names, and website names, when available, MLA no longer requires URLs. Writers are, however, encouraged to provide a URL if the citation information does not lead readers to easily find the source.
• Continuous Pagination? Who Cares? You no longer have to worry about whether scholarly publications employ continuous pagination or not. For all such entries, both volume and issue numbers are required, regardless of pagination.
• Publication Medium. Every entry receives a medium of publication marker. Most entries will be listed as Print or Web, but other possibilities include Performance, DVD, or TV. Most of these markers will appear at the end of entries; however, markers for Web sources are followed by the date of access.
• New Abbreviations. Many web source entries now require a publisher name, a date of publication, and/or page numbers. When no publisher name appears on the website, write N.p. for no publisher given. When sites omit a date of publication, write n.d. for no date. For online journals that appear only online (no print version) or on databases that do not provide pagination, write n. pag. for no pagination.

Some examples can be found by scrolling down here. “Son of Citation Machine” seems to have kept up with these changes, but be sure to use the correct documentation system and the correct type of source.