Sweet CRM

SugarCRM has just released version 2.5 of its open source CRM suite, SugarCRM.
SugarCRM is based on the LAMP (Linux-Apache-MySQL-PHP) architecture and runs on virtually every platform available, though the company prefers to promote Linux as its OS of choice. SugarCRM is freely available and can be downloaded from the company's site. SugarCRM Professional is the company's commercial offering of the suite, which adds functionality supportive of larger enterprises and includes a year of product upgrades as well as technical support (9x5) and the source code.
SugarCRM is also offered as a softpliance, on 1 or 2U form factor hardware running Red Hat Enterprise Linux WS 3.0 and MySQL Pro as well as the CRM software.

If that weren't enough, SugarCRM is also offered on-demand, hosted by SugarCRM as well as a list of partners (available on the corporate web site).

If you're interested, you can try out the open source version and grow into the professional, or if you're a PHP freak you can always modify the heck out of it yourself to fit your organizational needs.
The practice of commercializing open source software is not new. It's what Red Hat made its name from doing and what other a few enterprising vendors such as GlueCode have begun to do, but rarely do we see enterprise applications such as CRM or ERP in the open source arena so when we do, it's something to take note of and check out.