Ask HN: How problematic is Android device fragmentation?

In Apple's recent earnings announcement, Steve made the point that Android's many form factors and software flavors create a meaningful challenge for developers. Yet, the very company he used in his example - TweetDeck - joined the debate in a public tweet saying "Did we at any point say it was a nightmare developing on Android? Errr nope, no we didn't. It wasn't."

All that in mind, I'm curious what the HN community thinks: is it substantially more difficult to develop for Android relative to iOS? Are there any particular techniques or software packages that ease the burden?