I just installed Steam today on Ubuntu 10.10 / Maverick with Wine 1.3.11 and I'm getting the same end-all error.
(I can login, but Steam disappears after displaying the dialog window Connecting steam account: [username].")
Since you just posted this hours ago I'm going to guess a new Steam update messed up something.....
fixme:process:SetProcessShutdownParameters (00000100, 00000000): partial stub.
fixme:urlmon:CoInternetSetFeatureEnabled 5, 0x00000002, 1, stub
fixme:urlmon:CoInternetSetFeatureEnabled 10, 0x00000002, 1, stub
fixme:mixer:ALSA_MixerInit No master control found on HDA ATI HDMI, disabling mixer
err:ole:CoGetClassObject class {77f10cf0-3db5-4966-b520-b7c54fd35ed6} not registered
err:ole:CoGetClassObject no class object {77f10cf0-3db5-4966-b520-b7c54fd35ed6} could be created for context 0x1
fixme:wbemprox:wbem_locator_ConnectServer 0x20a3f0, L"ROOT\\CIMV2", (null), (null), (null), 0x00000080, (null), (nil), 0x42bbeb8)
fixme:winhttp:WinHttpGetIEProxyConfigForCurrentUser returning no proxy used
fixme:dbghelp:elf_search_auxv can't find symbol in module
