I was enjoying the new D4 all day, when I opened up a project that made
use of some components I had loaded via the dclusr.bpl.  It refused to
compile, and I found the reason was that the patch installation overwrote
all the dclusr.* files except the BPL in the BIN directory!  This made the
problem tough to find because it was still loading the BPL, and the
components showed correctly!
    I finally had to delete the BPL as well, then reload my components into
a new-named package, as I didn't know how to get a new dclusr without
re-installing!
    Just thought I'd mention this in case someone was getting perplexed!