Roundup: iPhone SDK gets more than 100,000 downloads, Yahoo may join OpenSocial and more

Here’s the latest action:

iPhone SDK gets more than 100,000 downloads — And that’s only in the first four days, according to Apple. The software development kit includes tools to build applications for the iPhone and the iPod, so the torrent of downloads means we could see a flood of exciting and innovative apps soon. (There will probably be some really terrible ones, too.) It’s also good news for Apple following some complaints that the SDK is too limited.

Yahoo to join OpenSocial? — TechCrunch is reporting that Yahoo has decided to join Google’s social networking platform, with an announcement coming in April. Yahoo has talked about opening up to third-party developers, but the move can also be seen as anti-Facebook (since that’s who OpenSocial is competing against, at least for now), or as a “screw you” to Microsoft, or both.

A hacker could break your heart (device) — A research team says it’s been able to gain wireless access to a heart device that’s a combined pacemaker and defibrillator. Theoretically, the team says it could shut the device down or steal personal data, although it needed more than $30,000 of lab equipment to make it happen.

How to run a start-up while keeping your day job — The short version: Don’t do it. The long version: If you must, here are some tips. Those include finding at least one co-founder, picking a day or two when you always work and making sure you’re not employed by a company that owns your after-hours work.

Disney makes $123M from iTunes — That includes the sale of 4 million movies and 40 to 50 million videos since 2006, says Disney chief executive Bob Iger.

Amazon launches Facebook apps — Amazon Giver shows your wishlist, while Amazon Grapevine creates an activity stream for actions you take on the site. Analysts are saying shopping could see major growth on Facebook this year, and both apps could be a big part of that.

Not everyone is an early adopter — It’s an obvious truth, but also an important one to remember, especially when you work in Silicon Valley. The New York Times offers a fun portrait of some late adopters, including a real estate agent who refuses to give up on Netscape.

Rush Limbaugh’s computer gets fixed — The conservative talk radio host’s previous on-air plea to Steve Jobs for tech help has apparently been answered, and he goes on at rather exhausting length about it. My eyes started to glaze over during the second paragraph, but before that I noticed Rush’s comments about how tech blogs seem to scrutinize his statements about Apple: “Any time I (talk) about Apple it’s just guaranteed that some of these blogs are going to blow gaskets … ”

VC firm DFJ Gotham looking to raise $125M fund — Silicon Alley Insider has the news.