I'm a newb when it comes to lossless codecs. So be gentle.

Are there any lossless codecs that support ID3 Tags? Or is that an mp3 only standard?

id3(v1+v2) is shit even for mp3
ape2 tags are best. they can be used for wav/mp3/mpc/monkeys audio (lossless) and probably many more. ogg vorbis uses a tagging system which is very similar to ape2. at least for me as a user (i'm not a programmer)

I'm pretty new myself, but AFAIK losless codec (like flac etc) have there own kind of tags (if any).
but there is an program that supports a whole lot of codecs: http://home.wanadoo.nl/~w.speek/tag.htm
you could use that to tag your files made with an losless codec (if that's what you had in mind, otherwise the topic would more belong to the losless codec section, I guess...)

>edit< ooops, it IS in that forum indeed, sorry >edit>

It says on FLAC's website (should anyone actually choose to read it) that id3v1 and v2 is supported in the winamp plugin but it is not part of the specs.