More details have emerged about the upcoming PC that Dell will make available with Linux as a stock option. In particular, they have released information on what sort of software configuration you can expect and what support will be included. They also make suggestions on what other hardware to purchase, such as suggesting that users stick to Dell printers with PostScript support, making printer installation easier. They also again mentioned their Linux support page, which includes a Wiki and hordes of information on what they do support and plan to support.
Support for many popular but proprietary codecs won't be included by default, which may be a source of some frustration. MPEG 1/2/3/4, WMA, WMV, DVD, QuickTime and others will all have no support by default, though it is possible to install support yourself. They are also planning to "re-evaluate" support for those sorts of media in the future. Missing support or not, it is a step in the right direction, and hopefully will be a popular enough choice for it to grow further.