To move
some apps to the SD card all you have to do is go to settings>applications>manage applications and then see which apps allow moving to the SD card. To move ALL your apps to the SD card you either need an app that may or may not be compatable with each app, or a ROM that allows force-installing to the SD card.
Apps2SD is native in Froyo, and the Android 2.2 SDK (software development kit) has been available to devs for a lot longer than even the rooters had access to leaked builds -- let alone source code -- but some devs haven't bothered to enable it (or have had trouble enabling it) for their programs. Of course, some apps in the market haven't been updated since Cupcake or Donut (Can't Google spell?
It's Doughnut!), let alone Eclair, so YMMV with an app from the market.