Attention baseball fans, the date that is no doubt etched in your brain — the start of the 2010 Major League Baseball Season — is fast approaching. To get you ready for April 4 (when the Boston Red Sox will take on the reigning World Series champion New York Yankees at Fenway Park) we’re pitching you five handpicked iPhone apps that will hit a home run with baseball fans.

If you are partial to America’s national sport — and let’s face it, it’s almost unpatriotic not to be — then these apps are an absolute must for your iPhone or iPod touch. However, in case we’ve struck out and missed any of your faves, then do let us know in the comments below.

1. MLB at Bat 2010

Although criticized for its $15 price tag, MLB’s official iPhone app is a great all-rounder for fans, and an even better option for fans that have a paid-up for MLB.TV because, with portable access to your MLB.TV account, you can watch live streaming games on the go. As with last season’s offering, anyone can use the app to listen live to games, as well as get a virtual idea of what’s happening at the park with MLB’s blow-by-blow Gameday updates.

The app also offers scores and stats, as well as some in-game highlights and a video library that’s searchable by both player and team. If you really can’t stretch to that $15, then a free “lite” version ( At Bat Lite) offers real-time MLB scores, schedules, news and standings — but no audio or video — that will keep you informed through to the end of 2010 World Series.

Cost: $14.99

2. FanGraphs Baseball

If you’re the type of fan that can rattle off ground ball to fly ball ratios and stolen base percentages like Rain Man reciting phone numbers, then quite simply you will love this app. Claiming to offer the most detailed player statistics available on an iPhone app, FanGraphs will let you look back and analyze every major player in baseball history, as well as look forward with live win probability graphs based on game data for the 2010 season.

Favorite players can be tracked with full, live box scores that link through to past stats, every play can be analyzed to see how it impacts the game, and there’s even up-to-date advanced fielding metrics via FanGraph’s “Ultimate Zone Ratings.”

Cost: $2.99

3. Ballpark Envi

It could be argued that the stadium is as much a character in baseball as the opposing teams or the crowd. A celebration of the nation’s ballparks is offered in one neat little app — Ballpark Envi — spanning baseball’s geography as well as its history from Shibe Park to the new Yankee Stadium. Browsable by team, or by American and National League, every current Major League baseball stadium is detailed with stadium pics and slide shows, seating charts (super useful for booking tickets) as well as the ability to see the park’s location on a map.

Whether you want to glimpse Dodger Stadium’s wavy roofs on the outfield pavilions or the orange foul poles of the Mets’ new Citi Field this app will give you an insider glimpse of America’s amazing ballparks with all their quirks and characteristics.

Cost: $0.99

4. iScore Baseball Scorekeeper

If you consider a baseball scorebook will set you back $5 at the absolute minimum (and more if you buy it at the park) then the $10 price tag for this app does not seem quite so steep. There are a dearth of 99 cent alternatives available in the App Store, but for looks and an intuitive interface (the app works on an “interview” premise asking you for all the data it needs to build a complete picture of the game) the iScore Baseball Scorekeeper is the champ.

As well as appealing to those hardcore fans that like to sit and score every game, this is also a good option for those new to baseball scorekeeping – you don’t have to learn all the abbreviations and symbols and iScore offers a full set of tutorial videos to get you using the app like a pro.

Cost: $9.99

5. Baseball Index Apps

If you want to keep your favorite Major League Baseball team in your pocket then offers an Index App for each and every MLB team. Working on the basis that being a fan is in fact misery (the agony of defeat and all that jazz) the apps make sure you are kept as absolutely up-to-date as possible with a comprehensive set of stats, opinions and news drawn from national and local papers, broadcast media and blogs.

One nice touch is that if a blog or news source you follow isn’t currently included in the indexing, the developer (Discover Motion) will add it in for you on request — just the kind of helpful option that warms the cockles of an iPhone owner’s heart.

Cost: $2.99 each

More iPhone resources from Mashable:

10 Essential iPhone Apps for Runners

10 Best iPhone Apps for Dog Lovers

Top 10 iPhone Apps as Judged by Mashable Readers

10 Fun iPhone Apps for Beer Lovers

Mashable’s New iPhone App: Download Today!

Image courtesy of iStockphoto, spxChrome

Reviews: Fangraphs, iStockphoto

Tags: Baseball, iphone, iphone apps, Lists, sports