Here i want to give you small tips when you decide to use -Current (the risk is on your own You have been WARNED!!)
The first thing you should do when you decide to use -Current is check your kernel version. The latest -Current will need 2.6.x kernel series (it's better if you have above 2.6.22.x. I used 22.214.171.124 currently at the time i wrote this post). Next thing is upgrade your glibc-solibs package. This is very crucial, since this package is the main C library being used by any other application. If you missed this steps, you may have unusable system, since every application you tried to execute will results in Segmentation fault. If you had this problem, i suggest you start reading Robby Workman's howto about GLIBC Recovery
The other package that you should upgrade at the beginning is pkgtool (the Slackware package management tools) and also sed. Some people said it's better to upgrade this three packages in single mode (runlevel 1), but i found it working at runlevel 3 (text mode), since i only have 2 accounts on my system (me and of course root). So if you have a running system with multiple accounts, i suggest to upgrade on single mode.
That's it. After upgrading glibc-solibs, pkgtool, and sed, you can start upgrading the rest of the packages using upgradepkg as usual. You can also remove packages that is no longer supported by looking at the CHANGES_AND HINTS file above.
Please note that -Current is very active in development terms, so it's very prone to changes. Here's the description about -Current:
Slackware-current is a snapshot of the active Slackware development tree. It is intended to give developers (and other Linux gurus) a chance to test out the latest packages for Slackware. The feedback we get will allow us to make the next stable release better than ever.
Please note that the code in this directory is unstable. It might be inconsistent about which version of the Linux kernel is required, could be incomplete because it's in the process of being uploaded, or might not work for other reasons. In most cases, we know about these things and are working to correct them, but still -- feel free to point out the bugs.
Production use is AT YOUR OWN RISK and is not recommended.
Security is NOT GUARANTEED. In -current, forward progress often takes priority. Security fixes take time and resources, and would often have to be done more than once. It's more efficient to build the system and secure it as time permits and/or the development cycle nears completion.
We do not promise to issue security advisories for Slackware-current.
Slackware-current might DELETE FILES WITHOUT WARNING when packages are upgraded. (If, for example, a directory location is replaced by a symbolic link to a new location.) Upgrade packages carefully. Examine incoming updates first if your machine's data is not expendable. Again, we do not recommend using Slackware-current to store or process valuable data. It is a system in testing, not one that is ready to go (though often it does work just fine... BUT DON'T COUNT ON IT)