LispWorks 5.1 brings these new features:

LispWorks as a dynamic library
64-bit Cocoa on Leopard, in 64-bit LispWorks
Improvements for Vista e.g. handle 256×256 icons
OLE embedding (LispWorks as ActiveX control)
New profiling API
Compiler help
Windows registry API
Improved AMOP compliance
Better handling of compilation conditions in IDE
IDE toolbars are optional
Better completion in IDE
New Search Files tool
Recent Files menu
Source location for user defining forms
Drag and drop support in CAPI
"Metafile" support in CAPI/Cocoa
Services and Dock menus supported on Cocoa
Various other new features, enhancements in CAPI and improvements in the IDE
Many bug fixes

See release notes

See website: now supports 64 bit systems.

See the release notes