Many fixes, and new features (keep-alive is the most 
important one). 

The next release (3.30) will soon be put in development 
phase, with new features (the most important one will be a 
Linux/Unix/BSD.. web-based, multi-language GUI))

List of features and fixes since 3.22-3:

3.23
+ New: Keep-alive
+ New: URLs size limit is now 1024 bytes
+ New: Bogus UCS2 html files hack
+ Fixed: base href bugs
+ Fixed: windows "dos devices" bug fixed
+ Fixed: dirty parsing now avoids ","
+ Fixed: "get non-html files near a link" option sometimes 
caused huge mirrors
+ Fixed: Bugs if zlib library is not found
+ Fixed: Bug with "near" and "no external pages"
+ Fixed: "Link empty" crash
+ Fixed: Several javascript bugs
+ Fixed: Keep-alive problems ("unknown response structure")
+ Fixed: Major keep-alive bug (connection not closed)
+ Fixed: 8-3 options not working, ISO9660 option improved
+ Fixed: Bogus links with embedded CR, TAB..
+ Fixed: small ../ external link bug fixed

Get it at:
<http://www.httrack.com/index.php?p=2>