A reminder: There are many more general reasons that you may have trouble emptying the Trash. And there are several solutions. For example, in replying to this issue, a couple of readers (Owen Hartnett and Jeff Donovan) noted that running Disk First Aid (even if it doesn't find any problems with the disk) can sometimes permit a file to be deleted that was otherwise stuck in the Trash. See the Troubleshooting chapter of the Macintosh Bible for more suggestions.
Last time, we described a problem with emptying the Trash when running Mac OS 8. Several readers (including Chris Glen, Kevin Craft and Paul Morrison) diagnosed the problem as due to SAM Intercept 4.5. Happily, they report that applying the SAM 4.5.1 Patcher fixed the problem (although this fact appears not specifically mentioned in any Info file for the Patcher). The samintup.sea.hqx patch reportedly also works.