Other vendors don't seem to be having trouble with supplying processors launched 2 months ago.
Other vendors who are going to ship at same volume? There have be a couple of reports here where at HP / Dell you could order, but they would ship later as got parts. Other vendors (e.g,. HP , Dell) still have older 3500/5500 models for sale. Apple's modus operandi is typically to dump the old and bring in the new totally across a very limited set of models. (either that or do "hand me downs" for higher to lower models. )
Similar to contributing reason to slow roll the Core i mobile roll out. When MacBookPros came either got a new Core i processor or didn't. There was no overlapping old/new offerings. Other vendors could do an earlier drop of a single Core i model while the other 5-10 models in their line ups still had older stuff. [ The Nvidia 320m's delayed release contributed too to the lower end of the lineup without the core i processors.]