As for BASH, it's still the same. Slackware still actively following the progress of BASH, but the default version hasn't change from the last release. Me myself has been using 3.2.048 and found no problem on my daily usage, but i'm not sure of upgrading to 4.0.024 for now.
Here's the latest -Current changelog:
Sat Jun 20 12:49:02 CDT 2009