Actually it doesn't work well on Ubuntu either. At least currently there is a problem when running 32-bit applications on 64-bit Ubuntu, for those whom are running 32-bit Ubuntu it should work fine though.
Anyway I'm not sure if "trayicon" is the best way to go. There are reasons for abandoning it on Ubuntu and also KDE devs have approved libappindicator (I don't know if KDE supports it yet).
https://wiki.ubuntu.com/DesktopExperienceTeam/ApplicationIndicators
There's a word about fallback in AppIndicators: https://wiki.ubuntu.com/DesktopExperienceTeam/ApplicationIndicators#Custom_Fallbacks
If you know of problems in libappindicator please report them to Canonical. That way everybody using app indicators gets an improved experience vs. Steam creating yet another implementation. Here's Canonical's statement.
Sorry to see that you have experienced a problem with Steam for Linux.
Steam includes application indicator support so that you can quickly access Steam's functionality within your panel. This appears in your panel as a small icon with a menu that appears when you click on it. This application indicator works in all versions of Ubuntu that Steam supports (12.04 and later) as well as many other desktops (such as KDE) and the distributions that ship those desktops.
If you run Steam under Ubuntu and you don't see the indicator, please report the bug to the Ubuntu developers. Doing this is simple; simply click the Ubuntu button, enter 'terminal' to load a Terminal, and enter the following command:
ubuntu-bug indicator-application
and follow the instructions. When asked for a summary, please enter 'libappindicator support for Steam is broken'. You may see that the bug has already been filed.
If you are using another distribution you should report a bug with your distribution with the same description. You should be able to find instructions for how to file your bug in your distribution's documentation.
Nothing extracted yet.
The current tray icon implementation based on libappindicator is really a bad choice because it works well only on Ubuntu with Unity.
You can get it working on other distributions/window managers but it has a lot of issues (lags, missing icon, dbus-related errors/warnings, ...).
Please, follow the freedesktop specification and consider implementing a standard tray icon, at least as the fallback for non-Unity systems, instead of the non-standard libappindicator one...