All of the above.
I currently have a Star Wars: Saga Edition play-by-post game that is currently on hiatus because dealing with combat and position was becoming too time consuming. Depending on how the DDI's tabletop works (most specifically, the subscription model -- if just the DM needs one, and it can hold a persistent state for viewing anytime, I'm golden), I'd love to resume this with some tabletop support to aid in the round-by-round. If I really luck out, the character creator will be able to do good approximations of Star Wars mood with glowing weapons and my (mostly) human/near-human party.
I'm about to start a 4e game (this afternoon, actually) that I would love to be able to supplement with DDI features. When the tools become available, I imagine at least a few of my players will go wild with the character creator, and I plan to abuse the hell out of it to create visual aids for interesting villains and the like. Depending on how easy/fast the tabletop is to use, it's conceivable that sometime in the future, we may eschew the battlemat and minis (or, more likely, battlemat and a frankensteined combination of minis, inappropriate minis, and pocket-foraged markers, to judge historically) in favor of a projected setup with my laptop, simply to replace the grid-bound stuff.
Furthermore, I've got a few friends I've made over the internet that I'd love to hook on D&D (including a couple that are already D&D veterans that I'd love to play with). I see the digital tabletop as potentially a great, comprehensive facilitator for just that. I'd love to add a weekly or semi-weekly online game on, say, Saturday nights to my regular in-person Sunday afternoon game.
Finally, if the tabletop's good, I could see killing an idle evening by rolling up a character for a one-off encounter or three with strangers. It's something I always wanted to have fun doing in NWN, but ended up dissatisfied with the rigidity of the system and the limitations of relying on typing speed and the game's UI when it came to facilitating roleplay or dealing with encounters. NWN really demanded a pre-scripted module, it's on-the-fly abilities were kind of disappointing.