Be careful when embedding fonts in Silverlight XAP file
There was a question on the Silverlight forums a while back where someone wanted to use the Tahoma font in their Silverlight application. http://silverlight.net/forums/p/20570/77555.aspx
Tahoma isn't included in the built in fonts, so one suggestion was to include the tahoma ttf file in the XAP file. I raised a red flag on that because of discussions I was involved with when XNA Game Studio first got text support. It turns out that you, as a user of Windows, do not have permission to redistribute the font files included with Windows.
There was some discussion about whether it was the same as embedding a font file in a Word doc, which you are allowed to do, but the difference is that the font file is obfuscated when embedded in a Word doc, so you can't easily extract the font file. In a XAP file (even if it's embedded as a resource in the DLL) it is trivial to extract the font file.
Stefan Josten followed up and contacted someone at Microsoft and received the response that you cannot in fact legally embed Tahoma in a Silverlight app without obtaining a license from the font author http://www.ascendercorp.com/inquiry.aspx?Ref=Microsoft
So if you're embedding fonts in Silverlight, make sure they are public domain or you have the license to redistribute them.
DISCLAIMER: I am not a lawyer and you should consult your favorite attorney about this or any other legal issue.