What GnuCash does deliver on though is support for usng an SQL database for storage of accounting regards rather than just an XML back-end. You can still use GnuCash with XML if you wish, but now SQLite3, MySQL, and PostgreSQL databases are now supported. This database interface uses libdbi.
GnuCash 2.4.0 also replaces the GtkHTML-based HTML renderer for reports and graphs to now using WebKit. The existing GtkHTML renderer can be used, but the WebKit-based renderer is the preferred path going forward.
That seems to be about it for GnuCash 2.4.0 besides some other minor work: auto-completion with the bill/invoice ledger, proper decimal separators on monetary amounts, and a number of bug-fixes. The full release details and download links are available at GnuCash.org, but it looks like most serious individuals and small businesses will still be bound to Intuit, PeachTree, Mint, and others going into 2011.