Only problem with that is you get a "brake light out" warning. I know its this way on the LS and the GS. The LS has a message center though, so I' not sure how it works on the cars without that readout. There were a lot of posts in the LexusLovers listbot about this. People even resorted to painting the plastic covering black.
I assume you have a spoiler with a high mount brake light right?