If you mean widgets downloaded from Apple, the short answer is no.
Dashboard, which hosts the mini-applications known as widgets became part of the OS with Tiger. There are approximately 5000 widgets available through Apple, but you do need Dashboard and therefore a minimum of OS 10.4.
The Yahoo widgets on the other hand, use what used to be known as Konfabulator - you can use it in 10.3.9.
http://widgets.yahoo.com/upgrade/Looks like there are just as many widgets too...
