Some info
A couple of comments here that may clear up an issue or two...
First, Apple is being forced to support the plus format, as the major, top line DVD manufactures are slowly merging the two formats.
In the beginning, there was a major compatibility issue, since the minus camp was planning on the R format being the primary recording medium, and the plus camp was planning on ReWritable being their primary medium. The plus camp even went so far as to not require finalizing the medium so that PC backups could happen quicker. Well that, and added the capability to erase individual files off of a disc.
Long and short, the plus camp saw that RW discs were nowhere near as compatible as the R medium, and decided to add it to the spec ( anyone with an old HP/Phillips RW only drive out there? ). Meanwhile, the minus camp did have RW, but it was not as heavily promoted, and later added a VR mode that also does not require finalizing the disc, but greatly reduces compatibility.
Once all of this happened, the largest manufacturers of drives realized that there was very little difference between the formats, and realized that splitting the recordable format would mean death to all. After all, Sony had a real problem when they used Pioneer minus drives in the Vaio PCs, but only sold plus drives over the counter.
Now... There is at least one company selling a burner that will burn the third DVD format ( RAM ), as well as the plus and minus DVD formats. You will find LG drives also sold under IOMEGA. The RAM format is a true data centric format, and as such, will not play in any DVD video player, with maybe the exception of a few Panasonic decks. Apple first supported this format, even though it has really never been a success.
In short, none of this will be an issue in about two years. People will buy a DVD burner, and the right medium to fit their recording needs. The formats are merging.
As for Apple ( remember them ). I have seen several times on MacNN that there is a firmware patch out there that will allow Laptop superdrive owners enable the faster CD burn speeds and enable the RW capabilities of the Panasonic drive they use. Apparently, Apple disables this ability due to wanting to conform to certain specs for the laptop ( power, heat, etc. ). I would not be surprised if they have done the same to the Sony drives they use too.
Here is the link to enable RW on the laptop superdrives, but be warned that your warrantee will not cover any damage that this patch may cause.
http://superdrive.cynikal.net/
I hope all of this helps.
Max