Developers outside of Google have created their own workarounds, such as a PHP-based unofficial API for reading and parsing public data from Google. However, what everyone is really waiting for is a full-blown equivalent to the Facebook platform, allowing social applications from other websites to be embedded within Google+ and Google+ features to be embedded in other websites.
Maybe Google is taking its time to make sure it gets this right. What's certain is that it's taking its time. M.G. Siegler at TechCrunch reports that Google Ventures startups are getting early access to some unreleased APIs--this, according to a memo he obtained, which also says that test phase will be "followed by a more general availability in the next few weeks." Siegler had previously reported that it's more likely to be months.
Although Google has disclosed few details about its plans, it's reasonable to expect it to include building blocks such as OpenSocial (which originated at Google) and OAuth 2.0. Google is also making use of the Open Graph Protocol, an open metadata standard most closely associated with Facebook. So developers can prepare by honing their skills for standards-based social software development.
The first Google+ games appear to use OpenSocial as at least one element of the integration API that Google provided to the developers, according to one student of the platform (note the semi-confirmations / non-denials in the message thread).
To stay up to date with the Google+ API rollout, start by adding your email to the waiting list for API access. You can follow the Google+ Platform blog, although there is not much there yet. Enrolling in the Google+ Platform Preview program also gives you access to a newsgroup where some announcements are rolling out, such as details on the Snippets microformat Google has introduced for use with the +1 button.
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