Licensing is a hot topic among type designers and type users alike. Type designers invest considerable time and effort in creating effective legible type and wish to protect their investment. Type foundries fear, justifiably, that their intellectual property may be downloaded from sites and used for unlicensed purposes. Self-hosting of embedded type makes it easy for unscrupulous users to either download the various woff eot and ttf or hotlink directly to them. For this reason, commercial services such as Typekit use various obfuscation methods to hide the url of their fonts while serving them.

A EULA typically grants the user a non-exclusive right to use the software (in this case, font). At no point does the user own the font. It will specify under which circumstances the font may be used. Most commercial EULAs either prohibit font embedding or require extended licensing. Many also prohibit their use in alternative technologies such as Cufón.

Web designers are clamoring for an elegant solution they can begin to implement that doesn't break EULAs.
― Craig Mod,

On the other hand, designers of typography want their audience to be able to view their type as intended. All fonts on Google Fonts Api, FontSquirrel and the league of Movable Type have EULAs which permit web embedding.
Nevertheless, at this time, the EULA and pricing models are probably the largest stumbling block to wider @font face adoption.

Bottom Line

Check the license with the font intended for use. This is equally true of freely available fonts, their EULA may permit personal or print use only. Use of a font outside of its EULA can leave users open to legal action.