Apparently so, if this article from ifmagazine.com is correct.

According to the report, producer Erwin Stoff (of The Matrix, A Scanner Darkly, and other high-profile projects) is currently developing a live-action Cowboy Bebop movie to be produced by Fox. Stoff goes on the record, saying:

"“I’m developing COWBOY BEBOP for Fox, but doing it as a live-action film, so I’m working on that at the moment,” Stoff tells iF. “I’m really excited to be working on it, and it’s in the really early stages. We just signed it the other day.”

Click on the link above to access the whole article, where Stoff also addresses concerns about fidelity to the source material and his thoughts on whether general audiences will warm to the movie's concept.

Considering that Cowboy Bebop is one of most popular anime series of all time in the West (though less so in Japan), there's likely to be a good amount of truth to this rumor. Of course, with the way Hollywood works, don't expect anything out of this until at least the next decade - if the project even takes off past the planning stage.