I'm excited because I've seen what Wizards does with their web site (sites, really - each game has one unto itself for all intents and purposes) already. Yes, you get your Realms Architecture articles representing the lowest ebb of Ed Greenwood's normally sterling career. You also get the wonderful Dragonshards articles from Keith Baker, though: articles that practically defined Eberron for many fans, and rightly so. You get a goodly amount of free adventures and article-length or longer supplements, often under the guise of 'web enhancements' (of which I think I have more than I have actual Wizards
books 
).
I'm excited because I've seen the D&D site's sister site, for Magic the Gathering, where the game designers put out their experiences, insight into the design process, reports on the metagame and plain old fun, along with the excellent Gatherer function. It's a great site that puts up tons of quality content
every day.
I'm excited because this move seems like a sign of Wizards being willing to take genuine risks - to wager they can do something that will anger some of the existing fanbase because the team at Wizards believe they can grab new fans. The last year or two of game design out of Wizards (culminating in Star Wars Saga, from the looks of it) has been the freshest in a long time, has been unafraid to explicitly put forth things like the warlock and the Bo9S in the face of controversy. The design work is excellent and the attitude of going for broke to attract new fans - who are likely to share more of my interests - is encouraging.
I'm excited because, unlike Dragon, which had fallen from its glory days as 'the magazine of the tabletop roleplaying' or even 'the magazine of fantasy' and become simply 'the magazine of D&D,' I think there's at least a chance Wizards will put up more content for d20 Modern and especially the new Star Wars Saga, as well as doing more to integrate their two excellent d20-based rules lite games, which are commonly misconstrued as collectible minis wargames.

Covering all of Wizards' d20 products isn't as good as covering EVERYTHING, but it's a lot better than covering only one thing. May Polyhedron rise again! At the same time, if a new gaming magazine appears in print now that there's no competition (I think it highly unlikely, but not impossible), it may become what Dragon used to be: a system neutral magazine that covers the industry as a whole.
I'm excited because I look at the team working at Wizards and know they do great work. A lot of content that might have slipped through the cracks because it didn't make it into a book may - with no production costs to hold it back - get put up in the new, online Dragon.