He is an exerpt copied directly from the book (I hope I'm not infringing on any copyright bizzo by doing this):

"A cuddled else keyword is no longer in vertical alignment with its controlling if, nor with its own closing bracket. This misalignment makes it harder to visually match up the various components of an if-else construct.

More importantly, the whole point of an else is to distinguish an alternate course of action. But cuddling the else makes that distinction less distinct. For a start, it removes the near-empty line provided by the closing brace of the preceding if, which reduces the visual gap between the if and else blocks. Squashing the two blocks together in that way undermines the paragraphing inside the two blocks, especially if the contents of the blocks are themselves properly paragraphed with empty lines between chunks." (Perl Best Practices . Conway, 2005; O'Reilly)

He goes on a bit more of course. While I admit not every developer sees eye to eye with the stuff in his book, I have been on a few projects that do use it as a style guide. This guideline is one that our home rolled linters enforce.