And now I will confess some important technical issues concerning the aforementioned uvular proposal for Proto-Indo-European (PIE). I still think that reinterpreting the non-palatal series of stops in traditional PIE reconstruction as uvulars is heading in the right direction. In this proposal, all we're really doing is pushing the articulation of all of the dorsal stops forward. By doing this, the exceedingly common palatal consonants thereby become plain and unmarked while the relatively much rarer "plain" consonants become uvular and marked. This solves markedness issues nicely by reversing which series is marked and which is unmarked with the least amount of effort. Yet...
There are a few problems and some extra ones that have been noticed by one observant commenter, Phoenix. Phoenix has commented in my last article that languages with uvular fricatives without velar ones are typologically unusual. And he's correct. I've also noted that a three-way contrast between uvulars that this proposal would require (namely *q, *q: and *ɢ for traditionally notated *k, *g and *gʰ, respectively) would also be quite rare. So it seems that the old, pre-Nietschean saying might be true: Damned if we do and damned if we don't.
But I'm not giving up on this brilliant uvular idea without a fight! It just makes too much sense and I think that getting rid of a large-scale oddness in phonemic distribution in favour of an odd typology with normal distribution between marked and unmarked phonemes is a positive trade-off. There are languages like French that lack a velar fricative but contain a uvular one instead. In French, the uvular trill as a favoured pronunciation of "r" sprang up recently in 17th-century Paris and this trend towards uvular-r, whether trill or fricative, gained popularity ever since, even in neighbouring languages like German, Dutch and Norwegian! If uvulars are really so odd in the grand scheme of things, it's rather amazing that this wave occurred. In Abkhaz (a language spoken in the Caucasus), there is a complex uvular stop series of qʲʼ, qʼ and qʷʼ without any non-glottalized counterparts! So we must realize that typological rarity is sometimes a matter of perspective. One must be reminded that areal environment often has a way of "concentrating oddities" in a single location and time as well.
Speaking of areal diffusion of curious phonological features, languages throughout the Caucasus mountains are known in fact to have these so-called "odd" uvular stops. For example, Lezghian of the Nakh-Daghestanian family contrasts aspirated uvular (qʰ), non-aspirated uvular (q) and ejective uvular (qʼ) stops. This is a 3-way contrast reminiscent of what I've suggested for an updated PIE. So that being said, is it too much of a stretch to wonder if perhaps pre-IE was inspired by these languages from the neighbouring Caucasus to adopt uvular phonemes?
I also find it interesting that, after I've suggested that uvularity was a rather recent distinct feature only developping from earlier allophonic variation once Syncope began in early Late IE, Lass' comments on phonemic typology appear to be quite apt: "Remembering that these are phonemic - not phonetic - 'normalcy statements', we can be justified in suspecting that, for instance, if a language has a pharyngeal fricative or uvular stop phonetically, it is more likely than not to be better characterized as an allophone of something else than a primary allophone." Indeed, I propose that MIE *k had two conditioned allophones, /k/ and /q/, and that it was only in the millenium preceding PIE proper where we find newly distinct phonemes *k and *q (traditional *ḱ and *k). For that matter, it didn't take long for *k and *q to merge in Centum dialects to plain *k while pushing forward to *ć and *k respectively in Satem dialects. This then seems like a more natural solution overall than the traditional account which would have us believe in palatalized velars which extend far into pre-IE despite being unstable and despite lacking any indication of a recent source of their supposed palatalization. The traditional account, keep in mind, is not just in violation of markedness in PIE itself, but in violation in the aeons preceding its theoretical development.
 Spencer, Phonology: Theory and Description (1996), p.16 (link here): "The uvulars are much rarer sounds than the velars, and it is especially rare for a language to have a uvular sound but no velar."
 Here, I use "colon" as a casual marker for 'fortis' stops. Don't take it literally as a geminate consonant, as might be the interpretation of those familiar with IPA notation. I suggest giving it the phonetic value of an unaspirated, possibly semi-voiced, stop.
 Gross, Speaking in Other Voices: An Ethnography of Walloon Puppet (2001), p.15 (link here).
 Lass, Phonology: An Introduction to Basic Concepts (1984), p.155 (link here): "In fact, one characteristic of areal and genetic groups is the way they often concentrate 'oddities': a particularly striking example is the virtual restriction of phonemic clicks to a portion of southern Africa. So what's rare universally may actually be the NORM for a family or area: we may have 'family universals'."
 Haspelmath, A Grammar of Lezgian (1993), p.2 (link here).
 Lass, Phonology: An Introduction to Basic Concepts (1984), p.155 (link here).
(Jan 7 2008) I added a footnote after questions about my uncommon colon notation for IE stops. Sorry, people. Sometimes I forget to explain these important details.