The new version uses both VPM and Buhlman. Comes with serious developments bundled with both DiveLog and GMP. Very easy to 'drive' and has intregral tools such as range plan, analysis mode etc. Re-planning made easy with one click.
Not cheep at $149 but the upgrade from previous version is cheeper.
http://www.gue.com/decoplanner/index.shtml
There is also Dplan for Palm at $49 which, to me, together with Mixer (free) makes the Palm a great diving unit.
http://www.gue.com/catalog/order/dplan.shtml
Izzy