Uh, not all of it. This point is often made by Graham Kerr, and sometimes Alton Brown mentions it. If having alcohol-free food is important to you, you need to request that specifically, and they'll simply not put the wine or liquor in in the first place (if they can).
Here's a chart of how much alcohol burns off versus how much is retained:
[font=verdana, geneva, helvetica]Alcohol Burn-off Chart
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[/font][font=verdana, geneva, helvetica]
Preparation Method[/font][font=verdana, geneva, helvetica]
Percent Retained
[/font] [font=verdana, geneva, helvetica]
alcohol added to boiling liquid & removed from heat[/font] [font=verdana, geneva, helvetica]
85%[/font]
[font=verdana, geneva, helvetica]
alcohol flamed[/font] [font=verdana, geneva, helvetica]
75%[/font]
[font=verdana, geneva, helvetica]
no heat, stored overnight[/font] [font=verdana, geneva, helvetica]
70%[/font]
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baked, 25 minutes, alcohol not stirred into mixture[/font] [font=verdana, geneva, helvetica]
45%[/font] [font=verdana, geneva, helvetica]
Baked/simmered dishes with alcohol stirred into mixture:[/font] [font=verdana, geneva, helvetica]
15 minutes cooking time[/font] [font=verdana, geneva, helvetica]
40%[/font] [font=verdana, geneva, helvetica]
30 minutes cooking time[/font] [font=verdana, geneva, helvetica]
35%[/font] [font=verdana, geneva, helvetica]
1 hour cooking time[/font] [font=verdana, geneva, helvetica]
25%[/font]
[font=verdana, geneva, helvetica]
1.5 hours cooking time[/font] [font=verdana, geneva, helvetica]
20%[/font]
[font=verdana, geneva, helvetica]
2 hours cooking time[/font] [font=verdana, geneva, helvetica]
10%[/font] [font=verdana, geneva, helvetica]
2.5 hours cooking time[/font] [font=verdana, geneva, helvetica]
5%[/font]
http://homecooking.about.com/library/archive/blalcohol12.htm