<p>Is there a way to call out from a TSQL stored procedure or function to a webservice?</p>

Not in T-SQL code itself, but with SQL Server 2005 and above, they've enabled the ability to write CLR stored procedures, which are essentially functions in .NET code and then expose them as stored procedures for consumption. You have most of the .NET framework at your fingertips for this, so I can see consumption of a web service possible through this.
It is a little lengthy to discuss in detail here, but here's a link to an
MSDN article
on the topic.