Fall Foliage
by Mike
Image Text: And I could replace you with older pictures of you, from back when you looked happy.
The hue of an image is the image's color or shade. The hue adjustment in Photoshop lets you move a slider back and forth to shift the colors of the image. This comic is suggesting that instead of taking the typical American trip to someplace like New Hampshire to see the leaves change colors in autumn, one could take a picture of summer leaves and just play with the hue slider in Photoshop to get a similar appearance. Of course, that wouldn't replicate my favorite part- the smell.
Surgery
by Jeff
Image text: Damn. Not only did he not install it, he sutured a 'Vista-Ready' sticker onto my arm.
This comic is a joke about the advances in Linux hardware/software support. "Eventually" there will be support for all sorts of hardware in Linux. As soon as an independent project picks up the case.
Unfortunately when he asked for a prescription for a free Windows 7 upgrade his insurance denied it.
Scribblenauts
by Jeff
Image text: Let me look away and type 'guy who's just jealous that I beat all his MarioKart times' and turn back, and ... yup, there you are again!
Scribblenauts is a side-scrolling game for the Nintendo DS in which you can summon objects to help you in the game, such as a ladder, or plants. "A fundamental element of Scribblenauts is the ability of the player to summon myriad objects into the game. This is achieved by writing the name of an object on the touchscreen (or via keypad)"
This comic takes that one step further and pokes fun at the prospect of summoning a friend in Scribblenauts by the phrase "Pretentious Asshole" or "guy who's just jealous that I beat all his MarioKart times"
The first two frames are making mention of the fact that there was some fear that the large hadron collider in CERN in Europe would create a black hole through their experiments. This was widely debunked, but apparently in Scribblenauts in xkcd, it does make a black hole.
Branding
by Jeff
Image meta text: Actually, 'RSS&M' is kinda catchy.
This comic is in reference to a Firefox extension called 'Adblock', which exactly as the name implies, blocks ads on websites. So, without Adblock, you will see all the ridiculous ads (except for our ads, they are great!) that attempt to get you to click on them with their catchy slogans.
The first two frames are not far off from reality, in fact I may have seen them before. Facebook and Twitter are widly known social networks. Google Reader is an RSS reader built on the google look and feel. The meta text references putting RSS and S&M together for RSS&M.
In the last frame, github is an online collaboration tool for developers to upload code to work with other developers on their projects. So, presumably, the comic is speculating that there will be a new GitHub, this one for only lesbians. This is the pop-up windows attempt to attract clicks and in the comics case, it might have worked.
This xkcd is one of the rare xkcd's to use color.