How do I Clean Putty out of Fabric/Carpet/etc.?
Silly putty sticks best to itself so take some additional silly putty (if you have any) and try to pull up the stuck putty by holding the good putty against the stuck putty for a second and then pull away quickly.
Once you get as much putty out as you can, put 99% pure alcohol on it. Not too much, just enough to reach all the silly putty. Let that stand a while and wipe it up with a clean cloth.
You should be able to get most of the silly putty up with this method followed up with regular cleaning.
You can also get silly putty stain removal tips from Crayola at:
http://www.crayola.com/canwehelp/staintips/stain.cfm
Their tips are a little different than this one but perhaps with a combination of the two you can get the job done.
If your clothes are synthetic, the alcohol is a very bad idea. So try the same thing, just use WD40 instead of alcohol.