InCD's UDF 1.02 to 2.01 discs should be read with success under Linux, at least that what we saw in our own tests.
UDF 2.50 is not supported by Linux hence InCD's discs formatted with this revision will not be readable by Linux. This is not an issue today as default UDF revision for CDs and DVDs are different from 2.50. This will soon be an issue with HD-DVD and BD who are likely to choose UDF 2.50 and/or 2.60 as standards. BD's recent DCN proposal to OSTA group was using UDF 2.50 for BD-ROM, -RE and non-POW -R, and UDF 2.60 for POW BD-R. This choice was approved by OSTA and included in UDF 2.60 document, itself expected to be official approved end of March.
There is no InCD Reader version for Linux so far. GPL license of current Linux UDF project makes it difficult for an ISVs to provide UDF support to Linux without given to competitors help you don't want to give them (or you'll get soon a business model issue
Linux UDF project has unfortunately a certain amount of bugs, fortunately publically available at: http://sourceforge.net/tracker/?group_id=295&atid=100295
Some are rather serious and marked with high priority. I fear that the project is currently missing an active developer to work on.