As already noted, iTunes 4.9 represents a milestone in the evolution of the product, and, more significantly, in the evolution of podcast availability and marketplace awareness. This version presents startling competition to iPodder and Audible.com. Accordingly, this brief review concentrates on the podcast fluency of iTunes 4.9; other features remain pretty much the same. (Worth noting, however, are reports from Mac users that 4.9 redirects the location of the music library, wiping out playlists. That's a serious issue I've been reading about on the Pho list, but have not investigated further. This is a Windows-only household, and the upgrade to 4.9 was smooth and damage-free.)

Podcasts are tucked into tight integration with the iTunes Music Store in 4.9; they are represented as a genre. Further drilling into categories of podcasting (Audio Blogs, Comedy, Humor, Public Radio, etc.) occurs within the podcast iTMS genre. On the front page of iTMS within iTunes, selected podcasts are featured; they are the usual suspects: Dawn and Drew; Daily Source; etc..

By default, listening to a podcast is a streaming experience in iTunes. That is to say, double-clicking on a podcast title forges a connection and plays the podcast without downloading it. Actually acquiring the thing is a bit confusing. Users can click the SUBSCRIBE button next to any show in the directory; this downloads the most recent edition of the podcast and marks it for future downloads. (The user sets the frequency with which iTunes checks for new podcasts in the Preferences panel. The setting can be left on Manual, so that no downloads are ever invoked automatically.) But subscribing might seem a little too committed when checking out a new podcast. To get a single episode without subscribing, you must click a tiny arrow icon to bring up an information panel, than click a GET EPISODE button that finally appears. That button should appear in the directory, next to the SUBSCRIBE button. (Or the placement of the two buttons should be reversed.)

At any rate, once these wrinkles are understood, the desktop podcast-listening experience is fantastic. One feature that I didn't expect, but which is fully present, is intra-podcast bookmarking: iTunes tracks where in the podcast you stopped listening. On your next double-click of that episode, iTunes picks up where you left off. Naturally, this player-specific feature does not export to iPods. But it sure is fun (and useful) on the desktop to bounce around among podcasts without missing a single word or note. (The bookmarking is necessary, I might add, because iTunes does not allow you to listen to one podcast while browsing the podcast directory; every time you look at a new category the playback stops.)

To keep track of all this, a Podcasts item has been added to the left-hand pane in iTunes, beneath the Library icon. Clicking it displays a sensible arrangement of podcast titles, each of which is expandable to show which episodes have been downloaded. You can mark each episode as played or unplayed, and tweak the display in other ways.

A few bugs infect the 4.9 experience.

• In the podcast directory, the Get Info selection in the right-click menu invariably brings up "Not Available," even for podcasts currently playing (!). Yet, the same Get Info selection in the Podcasts pane (after a podcast has been selected for streaming or download) brings up the Info panel with no trouble.

• The SUBSCRIBE button appears next to some, but not all, of the podcasts I have placed on the Podcasts display; it is not immediately apparent what determines the presence of that button.

• I found the entire music store to be unavailable a couple of times while testing 4.9.

• Finally (and this is more an insufficiency than a bug), the selection of podcasts is unaccountably sparse. Many more genre categories are necessary (one big Music category absolutely doesn't cut it), and many more podcast titles.

Never mind the drawbacks for now. iTunes 4.9 is a blazing and timely success; should send panicky shivers to the developers at iPodder and Audible.com. I can hardly believe I'm raving about iTunes, but all credit where credit is due. This thing is a breakthrough, landmark product. iTunes 4.9 has instantly become a staple program on my desktop; before this release I opened iTunes once every few months, and usually regretted doing so. It will not replace my Winamp or encroach on my music-listening tools. But it shoves the unpredictable vagaries of iPodder right out of my life, and becomes the only podcast aggregator I need.