<p>Some programming languages such as Java and C# include encryption packages in their standard libraries.  Others such as Python and Ruby make you download third-party modules to do strong encryption.  I assume that this is for legal reasons; perhaps Sun Microsystems has enough lawyers that they aren't afraid of getting sued, while Guido van Rossum feels more vulnerable.</p>

<p>But what does the law actually say about this?  At this point, would open source authors have anything to fear if they included strong encryption in their programming languages' standard libraries?  If so, then why don't they?  If not, then how do Sun and Microsoft get away with it.</p>

IANAL, But...
Java and C# are closed-source, and thus have terms in the EULA that say more-or-less "It's not our fault if you use this somewhere you're not supposed to". They also have teams of lawyers to protect themselves and enforce that clause.
Most open-source licenses do not have similar langauge, and even the ones that do, they don't have teams of lawyers on their side, as the OP said.
Also, Python and PERL are older than Java and C#, from the days when it was illegal to export cryptographic software from the US. Not adding cryptography since the law was changed is perhaps simply a "consistency-is-good" decision.