I was browsing through the tags on Gaming.SE to see if I could add any tag wiki excerpts (y'know, with the new tagging system and all), and I noticed some of the excerpts began with capital letters, and some didn't. I thought this might have been specific to Gaming for some reason, so I checked Meta Stack Overflow's tags, and, similar to Gaming's tags, some entries began with capital letters and some didn't. However, I found that Stack Overflow's tag wiki excerpts almost always seem to begin with lowercase letters (unless, of course, they began with a proper noun).
I feel all the tag wiki excerpts should be consistent (especially now that they're shown when tagging questions), so my question is should the first letter of tag wiki excerpts be capitalized or not?