It's easy to install nVidia or ATI drivers for graphic cards, just wait that Ubuntu detect it and propose you to install a proprietary driver. I've just change my old nVidia card with a new ATI with no problem.
But when you want to add a new printer... (Brother in my case) there is no easy way, why?
Printer drivers are userspace things, they don't exist in the kernel, and they're also not part of the X stack. The kernel, xorg and desktop developers have an interest in making sure video drivers work and install easily because without them, well, you can't see much. Printers are relatively rare peripherals compared to video cards. Everyone has a video adapter, not everyone has a printer.
Plus there's a much wider diversity of printers than there are video cards. People tend to keep printers for longer than they keep video cards, because printers are often useful beyond the few years that a video card is "current" for.
The other factor is the wide diversity of hardware vendors. For video cards there's really only three main players, Intel, nVidia and AMD/ATI, with a lot of smaller companies like VIA and neomagic. There's a gazillion printer manufacturers out there, and each one has a bazillion printers to make drivers for (although most are very similar). Net result is that each printer vendor has their own license terms, driver installation method and relationship with the open source community.
Some vendors 'get it', others don't. I'd recommend contacting the vendor of your printer and letting them know that "ease of driver install" is one of the factors you use when making a decision about which printer to buy in the future.
Popey has some good tips on why this is.
The Linux Foundation maintains a database of printers and drivers that show you how well the manufacturer supports Linux. In the case where the printers are well supported with drivers Ubuntu will fetch the drivers for you (Using Jockey, the same tool that recommends the video drivers) and the user experience is great.
When manufacturers don't support Linux either it will be missing from that list entirely or they will put some blob on their website somewhere with varying degrees of difficulty for the end user.
there is:
menu -> system -> Administration -> Printing
then you press the add / new button, and it searches for you :)